What causes tire blowouts in summer and how do I recover from one?

Summer heat causes tire blowouts through two mechanisms. First, hot pavement transfers heat to the tire, raising its internal temperature and pressure. A tire that is already underinflated flexes more with each rotation, generating additional heat from the repeated bending of the sidewall. The combination of ambient heat and flexion heat can push the tire's internal temperature past the point where the rubber and structural cords fail. Second, tires with insufficient tread depth, sidewall damage, or dry rot from UV exposure are structurally compromised and more likely to fail under thermal stress. To recover from a blowout: grip the steering wheel firmly with both hands, do not brake, do not jerk the wheel, ease off the accelerator gradually, and let the vehicle slow on its own. Steer gently toward the shoulder using small corrections. Apply brakes lightly only after the vehicle has slowed below 30 mph. The two most dangerous instincts are hard braking and overcorrecting the steering, both of which can cause a loss of control or rollover.

How fast can a car interior heat up and what temperature can it reach?

According to research published in the journal Pediatrics and data from the National Highway Traffic Safety Administration, a vehicle's interior temperature can rise 20 degrees Fahrenheit in just 10 minutes, even with the windows cracked. On a 90-degree day, the interior can reach 109 degrees in 10 minutes, 119 degrees in 20 minutes, and over 130 degrees within 30 to 60 minutes. On a 70-degree day that might feel comfortable outside, the interior can still reach over 100 degrees. The dashboard and steering wheel, which absorb direct sunlight, can reach 150 to 180 degrees Fahrenheit. Children are especially vulnerable because their bodies heat up three to five times faster than adults. Since 1998, over 900 children have died from vehicular heatstroke in the United States, according to noheatstroke.org. Never leave a child or pet in a parked vehicle, even for a few minutes, even with the windows cracked, even in the shade.

When are wildlife crossings most likely during summer?

Wildlife-vehicle collisions peak during two periods: October through December during deer mating season, and May through August when animals are most active during long daylight hours and young animals are dispersing from their birth areas. According to the Federal Highway Administration, there are an estimated one to two million wildlife-vehicle collisions annually in the United States, causing approximately 200 fatalities and over 26,000 injuries. Dawn and dusk are the highest-risk times because many large animals, including deer, elk, and moose, are crepuscular, meaning most active during twilight hours. Summer driving at dawn and dusk through rural areas, near forests, and along roads that parallel waterways requires heightened attention. If a large animal is in or near the road, brake firmly in your lane. Do not swerve. Swerving to avoid a deer at highway speed frequently causes a more serious crash than the animal strike itself, including rollovers and head-on collisions with oncoming traffic.

How should I prepare my vehicle for a long summer road trip?

Start with the systems that heat stresses most. Check tire condition, tread depth, and pressure including the spare. Inspect belts and hoses for cracking, swelling, or soft spots, which are signs of heat degradation. Verify the coolant level and concentration with a test strip or refractometer. Test the battery, especially if it is more than three years old, because summer heat degrades batteries faster than cold does. Check that the air conditioning blows cold at its coldest setting. Top off washer fluid and verify wiper blade condition. Check all lights. Under the vehicle, look for any fluid drips. Check the engine oil level and condition. If you are towing or carrying a heavy load, verify that your tire pressure matches the loaded recommendation on the door jamb sticker, which is often higher than the unloaded pressure. Carry at least one gallon of water per person per day for the length of your trip, plus extra engine coolant and a basic tool kit.

Home Self-reliance Transportation Summer Driving

When transportation fails

Summer Driving: Heat, Tire Blowouts, and Long Distances

Q: What should I do if my engine overheats while driving?

If the temperature gauge rises above normal or a warning light activates, immediately turn off the air conditioning and turn the heater to maximum with the fan on high. This sounds uncomfortable, but the heater core acts as a secondary radiator, pulling heat from the engine coolant and dissipating it into the cabin. If the temperature continues to rise, pull over safely and turn off the engine. Do not open the radiator cap while the engine is hot. The cooling system is pressurized, and opening the cap can cause a steam explosion that sprays boiling coolant. Wait at least 30 minutes for the engine to cool before checking the coolant level. If the coolant reservoir is empty, the system has a leak. Adding water can get you to a repair shop, but do not drive far on water alone, and never pour cold water into a hot engine, which can crack the engine block from thermal shock.

Heat does not announce itself the way ice does. It works quietly on your tires, your engine, your battery, and your passengers until something fails. Understanding what heat does to a vehicle, and what it does to people inside one, is essential summer driving knowledge.

The reality

Different risks, not smaller ones

Summer feels like the safe season for driving. The roads are dry, visibility is good, and there is no ice. But summer has its own set of mechanical failures and human hazards that are less dramatic than a winter storm and just as capable of stranding you or causing a crash. Tire blowouts peak in summer because heat is the primary driver of tire failure. Engine overheating peaks because the cooling system is working at maximum load. Batteries die in summer more often than winter, despite the common belief that cold is harder on batteries, because sustained heat accelerates the internal chemical degradation that eventually kills the battery.

Summer also brings the highest traffic volumes of the year. The combination of vacation travel, longer daylight hours encouraging longer drives, more motorcycles and bicycles on the road, more pedestrians in crosswalks, more construction zones, and more wildlife activity creates a driving environment that demands attention even when the weather is perfect.

According to NHTSA, more traffic fatalities occur in summer months (June through September) than any other period. The dry roads and clear skies encourage higher speeds, longer trips, and a level of comfort that can shade into inattention. The risks are real. They are just quieter than winter's.

What heat does

How heat attacks your vehicle

Tires: the most vulnerable component

Pavement temperatures on a sunny summer day can reach 130 to 150 degrees Fahrenheit, even when the air temperature is only 90 degrees. That heat transfers directly into the tire rubber with every rotation. Inside the tire, air pressure rises as the temperature increases, roughly 1 psi for every 10 degrees Fahrenheit of temperature change. A tire inflated to a correct 35 psi in a 60-degree garage may read 39 to 41 psi after highway driving on a 95-degree day.

That pressure increase is normal and expected. The danger comes from underinflation. A tire that starts the day at 28 psi instead of 35 psi flexes excessively with every rotation. Each flex generates heat in the sidewall. That internally generated heat, added to the heat absorbed from the pavement, can push the tire past its thermal limit. The structural cords that hold the tire together weaken and eventually fail. The result is a blowout, a sudden, violent loss of air that can shred the tire and leave you controlling a vehicle on three tires and a bare rim at highway speed.

Tread depth matters too. Tires with less than 4/32 of an inch of remaining tread are significantly more likely to fail in summer heat because the thinner rubber provides less thermal mass and less structural support. The legal minimum of 2/32 is the bare minimum for wet-road traction. For heat resistance, replace tires before they reach 4/32.

Check tire pressure monthly and before any long trip, when the tires are cold, meaning they have not been driven more than a mile. Use the pressure listed on the driver's door jamb sticker, not the maximum pressure on the tire sidewall. The door jamb number is the vehicle manufacturer's recommendation for the correct balance of load capacity, ride quality, and tread wear.

Engine cooling system

Your engine generates enormous heat during normal operation. The cooling system circulates coolant through the engine block, absorbing that heat and dissipating it through the radiator. In summer, the cooling system works harder because the ambient temperature is closer to the engine's operating temperature, which means the radiator has a smaller temperature differential to work with. Add a steep hill climb, stop-and-go traffic, towing a trailer, or a fully loaded vehicle, and the cooling system may reach its capacity limit.

The most common cooling system failure is a coolant leak, either from a deteriorated hose, a failing water pump seal, a corroded radiator, or a loose clamp. A slow leak may not cause problems in winter, when the system is under less thermal stress, but in summer the same small leak can drop the coolant level enough to cause overheating. Check the coolant level in the overflow reservoir regularly during summer. If it drops between checks, look for wet spots or stains under the vehicle where it parks.

Coolant condition matters. Coolant breaks down chemically over time, losing its anti-corrosion properties and its ability to transfer heat efficiently. Most manufacturers recommend replacing coolant every 30,000 to 50,000 miles or every three to five years, whichever comes first. If your coolant is more than three years old and has never been replaced, a flush and refill before summer is a reasonable precaution.

Battery

The common belief is that cold weather kills car batteries. In reality, summer heat does most of the damage. High under-hood temperatures accelerate the chemical reaction inside the battery that produces electricity, but they also accelerate the internal corrosion and electrolyte evaporation that degrade the battery's capacity permanently. A battery that survives a hot summer may fail the following winter, not because the cold killed it, but because the summer heat weakened it to the point where the cold's additional demand was more than it could handle.

If your battery is three years old or older, have it tested before summer. Auto parts stores test batteries for free. If the battery tests below 80% of its rated cold cranking amps, it is approaching the end of its useful life and may fail during a heat wave, leaving you stranded in a parking lot at the worst possible time.

Belts and hoses

Rubber components under the hood degrade in heat. Serpentine belts, radiator hoses, heater hoses, and other rubber components develop cracks, soft spots, and swelling that are visible on inspection but easy to miss if you do not look. A belt that breaks disables the water pump (causing immediate overheating), the alternator (causing the battery to drain), and the power steering pump. A hose that bursts dumps the coolant on the road and causes overheating within minutes.

Inspect belts and hoses visually before summer. Squeeze the hoses. They should feel firm and springy, not soft, mushy, or swollen. Look at the belt surfaces for cracks, fraying, or glazing. If a belt or hose looks questionable, replace it. These components are inexpensive compared to the cost of an overheating-related breakdown, which can include towing, a hotel stay, and potentially engine damage.

Air conditioning

The A/C system is not a luxury in summer. In extreme heat, it is a safety system. Interior temperatures in a vehicle without functioning air conditioning can reach dangerous levels for the driver, causing heat exhaustion that impairs reaction time, judgment, and alertness. If your A/C is blowing warm or not as cold as it should be, have it serviced before summer travel. The most common issue is low refrigerant from a slow leak, which is a straightforward repair.

Emergency response

Tire blowouts: physics, response, and prevention

A blowout is a sudden, explosive loss of tire pressure. Unlike a slow leak, which allows time to pull over and address the problem, a blowout happens in a fraction of a second. The tire shreds, the vehicle lurches toward the side of the blowout, and the driver must respond correctly in a moment when every instinct says to do the wrong thing.

What happens during a blowout

When a front tire blows, the vehicle pulls sharply toward the blown tire because the deflated tire creates more rolling resistance than the inflated one. The steering wheel may jerk out of your hands if your grip is loose. When a rear tire blows, the rear of the vehicle may sway or fishtail. The vehicle feels unstable and the steering may feel vague because the rear tires are no longer providing directional stability.

The noise is dramatic: a loud bang followed by a flapping or thumping sound as the shredded tire contacts the wheel well and road surface with each rotation. The vehicle's behavior changes instantly. These sensory inputs trigger a panic response in most drivers, which is exactly why the correct procedure must be practiced mentally before it is needed.

The correct response

Grip the steering wheel firmly with both hands. This is the most important action. A front blowout will try to pull the wheel out of your hands. A firm grip keeps the vehicle going in the direction you choose rather than the direction the blowout wants to send it.

Do not brake. This is the hardest part because braking is the instinctive response to any emergency. Braking during a blowout shifts weight to the front of the vehicle, unloading the rear wheels. If the blown tire is in the rear, braking can cause the rear end to swing out. If the blown tire is in the front, braking increases the load on the already-damaged tire and can cause the rim to dig into the pavement, pulling the vehicle further off course.

Ease off the accelerator gradually. Let the vehicle slow on its own through wind resistance, rolling resistance, and the drag of the blown tire. Some driving instructors actually recommend a brief, gentle application of the accelerator immediately after the blowout to stabilize the vehicle before beginning the deceleration. The logic is that a slight forward drive force counteracts the drag of the blown tire and helps maintain directional stability. Whether or not you apply that technique, the key principle is the same: gradual deceleration, not abrupt braking.

Steer gently toward the shoulder. Use small, smooth steering corrections. The vehicle will resist turning toward the side with the good tire because the blown tire creates more drag. Make the corrections gradual. A large, sudden steering input can cause the rim of the blown tire to catch on the pavement and send the vehicle into a spin.

Apply brakes lightly only below 30 mph. Once the vehicle has slowed to parking-lot speed, gentle braking is safe. Pull completely off the road, turn on hazard flashers, and assess the situation.

Prevention

Most summer blowouts are preventable. The three factors that cause blowouts, underinflation, worn tread, and aged rubber, are all detectable through routine inspection.

Pressure. Check tire pressure monthly and before any long trip, using a gauge, when the tires are cold. The correct pressure is on the driver's door jamb sticker. A tire that is 5 psi underinflated looks normal to the eye but flexes enough to generate dangerous heat at highway speeds. Do not rely on the tire pressure monitoring system (TPMS) as your only check. TPMS warning lights typically activate at 25% below the recommended pressure, which means the tire can be significantly underinflated before the system warns you.

Tread depth. Tires with tread below 4/32 of an inch have reduced heat resistance and reduced wet-road traction. Use a tread depth gauge or the quarter test: insert a quarter upside down into the tread groove. If you can see the top of Washington's head, the tread is at or below 4/32 of an inch and the tire should be replaced. The legal minimum of 2/32 is a bare-minimum safety standard, not a recommended replacement point.

Sidewall inspection. Look at the sidewalls for bulges, cracks, cuts, or any visible damage. A bulge indicates internal structural damage where the tire cords have broken, creating a weak spot that can fail suddenly under heat and pressure. A cracked sidewall indicates dry rot from UV exposure and age. Either condition makes the tire a blowout risk and warrants immediate replacement.

Tire age. Replace any tire that is more than six years old regardless of remaining tread. UV exposure and heat cycling degrade the rubber compounds over time, reducing flexibility and structural integrity even if the tire has been stored indoors. The manufacture date is stamped on the sidewall in a four-digit DOT code: the first two digits are the week, the last two are the year. A code of 2319 means the tire was made in the 23rd week of 2019. A tire made in 2019 reaches its six-year replacement point in 2025, regardless of mileage or visual condition.

The spare. Check the spare tire before any summer trip. Spare tires, especially compact temporary spares, lose pressure over time and may be flat when you need them. The spare is also subject to age degradation. A spare tire that has been sitting in the trunk for ten years may look fine but have compromised rubber that cannot be trusted at highway speeds.

Emergency response

Engine overheating: the warning signs and what to do

An overheating engine is a time-critical emergency. The engine block, cylinder head, and head gasket are designed to operate within a specific temperature range. When the coolant temperature exceeds that range, metals expand unevenly, gaskets fail, and the engine can suffer permanent damage within minutes. A head gasket failure alone can cost $1,500 to $3,000 to repair. A warped cylinder head or cracked block can total the engine.

Warning signs

The temperature gauge climbing above the normal range is the primary warning. Most gauges have a clearly marked normal zone and a red zone. Some modern vehicles have replaced the gauge with a warning light that activates when the coolant temperature exceeds a threshold. Either way, the message is the same: the engine is too hot and you need to act now.

Other signs: steam or vapor rising from under the hood, a sweet smell from evaporating coolant (ethylene glycol has a noticeable sweet odor), a hot smell from the engine compartment, or loss of power as the engine management computer reduces performance to protect the engine.

Immediate response

Turn off the air conditioning. The A/C compressor adds load to the engine and the condenser (mounted in front of the radiator) adds heat to the air flowing through the radiator. Turning off the A/C reduces both.

Turn the heater to maximum with the fan on high. The heater core is a small radiator inside the dashboard that uses engine coolant to heat the cabin. Running the heater at maximum draws heat from the coolant and dissipates it into the cabin. This is genuinely effective at reducing coolant temperature. It is also genuinely uncomfortable on a summer day. Accept the discomfort.

If the temperature continues to rise, pull over and turn off the engine. Continuing to drive an overheating engine risks catastrophic damage. Find a safe place to pull off the road, turn off the engine, and open the hood to allow heat to escape. Leave the hood up but do not touch the radiator cap, coolant hoses, or engine surfaces. Everything under the hood is at scalding temperatures.

Do not open the radiator cap while the engine is hot. The cooling system operates under pressure, typically 13 to 18 psi. Opening the cap while the system is hot and pressurized releases that pressure explosively, spraying boiling coolant and steam that can cause severe burns. Wait at least 30 minutes, or until the engine is cool enough to touch the upper radiator hose without discomfort, before opening the cap.

Check the coolant level after cooling. If the overflow reservoir is empty, the system has lost coolant through a leak. Adding plain water can get you to a repair shop but is not a permanent fix. Never pour cold water into a hot engine. The thermal shock from cold water contacting hot metal can crack the engine block or cylinder head.

Situations that cause overheating

Stop-and-go traffic in heat. At highway speed, air flows through the radiator and dissipates heat effectively. At idle or low speed, the only airflow through the radiator comes from the electric cooling fan, which moves much less air. Extended idling in traffic on a hot day is one of the most common overheating scenarios.

Steep climbs and towing. Climbing a long, steep grade puts the engine under sustained high load, generating more heat than level driving. Combined with summer temperatures, this can overwhelm a cooling system that is marginal. Towing multiplies the effect: a trailer adds hundreds or thousands of pounds of load that the engine must move, generating proportionally more heat. A vehicle that never overheats around town may overheat consistently when towing a boat up a mountain grade on a 95-degree day. If you tow in summer, watch the temperature gauge on every sustained climb. Turn off the A/C and use the heater trick early, before the gauge enters the danger zone, rather than after. Some truck and SUV owners install auxiliary transmission coolers and larger radiators specifically for summer towing. For any vehicle, reducing speed on long climbs while towing reduces engine load and heat generation significantly.

Low coolant. Even a small reduction in coolant level reduces the system's ability to transfer heat. Air pockets in the cooling system insulate rather than cool, creating hot spots that can damage the head gasket. Maintaining the correct coolant level is the simplest and most effective overheating prevention.

Life safety

Heat inside a parked vehicle: children, pets, and passengers

A parked vehicle in direct sunlight becomes a greenhouse. Glass transmits visible light, which is absorbed by the dashboard, seats, and interior surfaces and re-radiated as infrared heat that the glass traps. According to NHTSA and research published in the journal Pediatrics, a vehicle's interior temperature can rise 20 degrees Fahrenheit in just 10 minutes. On a 90-degree day, the interior reaches 109 degrees in 10 minutes, 119 degrees in 20 minutes, and can exceed 130 degrees within an hour.

Cracking the windows does not solve the problem. Studies have shown that partially open windows reduce the peak interior temperature by only a few degrees. The rate of temperature rise is essentially the same. Parking in the shade helps but does not eliminate the risk, because shade can shift as the sun moves and the greenhouse effect still operates through diffuse light.

Children

Children's bodies heat up three to five times faster than adults. Their thermoregulatory systems are less developed, they have a higher surface-area-to-body-mass ratio, and they cannot remove their own clothing, open doors, or call for help. Heatstroke in a child can progress from discomfort to organ failure within minutes at interior temperatures above 104 degrees.

Since 1998, over 900 children have died from vehicular heatstroke in the United States, according to tracking by the National Safety Council and noheatstroke.org. More than half of those deaths involved a caregiver who forgot the child was in the vehicle. This is not carelessness. It is a well-documented failure of prospective memory, the brain's system for remembering to do something in the future, that can affect anyone under stress, sleep deprivation, or a change in routine.

Prevention habits. Place something you will need at your destination, such as your phone, bag, badge, or left shoe, in the back seat next to the child seat. This creates a physical reminder that interrupts the autopilot of your routine. Some parents keep a stuffed animal in the child seat and move it to the front passenger seat when the child is in the car, creating a visible cue. Make it a habit to always check the back seat before locking the vehicle, even when you know the child is not with you. Building the habit means it fires automatically on the day your routine changes.

Pets

Dogs and cats cannot cool themselves as effectively as humans. Dogs pant to evaporate moisture from their tongues and respiratory tract, but this mechanism fails in a hot, enclosed space where the air itself is superheated and saturated with moisture. Heatstroke in dogs can begin at body temperatures above 104 degrees Fahrenheit and become fatal above 107 degrees.

The same rules apply to pets as to children: never leave them in a parked vehicle in warm weather. If you are traveling with a pet, plan your stops so that the pet is never left in the vehicle. Use drive-through options where available. Bring a second person who can stay with the pet while you go inside. If you must leave the pet briefly, take the animal with you.

If you see a child or pet in a hot vehicle

Call 911 immediately. Note the vehicle's make, model, color, and license plate. Many states have Good Samaritan laws that protect bystanders who break a vehicle window to rescue a child or animal in imminent danger of heatstroke. The legal specifics vary by state, but the moral calculus is clear: a broken window is replaceable. A child is not.

Long distance

Road trip preparation: long distances in summer heat

Summer is peak road trip season. AAA estimates that over 50 million Americans travel by car for the July Fourth holiday alone. Long-distance summer driving combines sustained heat exposure for the vehicle, extended driving hours for the driver, heavier loads than normal, and unfamiliar roads. Each factor multiplies the others.

Vehicle preparation

Start with the systems that heat stresses most. Check all five tires, including the spare, for tread depth, sidewall condition, and correct pressure. Inspect belts and hoses visually and by feel. Check coolant level, concentration, and condition. Test the battery if it is more than three years old. Verify the A/C produces cold air at its maximum setting. Check all exterior lights. Top off washer fluid. Check engine oil level. Look under the vehicle where it parks for any fluid drips that indicate a leak.

If your vehicle is due for any scheduled maintenance, such as an oil change, transmission service, or brake inspection, do it before the trip rather than after. A road trip puts more sustained stress on a vehicle than normal daily driving, and a component that is marginal but functional around town may fail on a 500-mile highway drive in 95-degree heat.

Loading the vehicle

A fully loaded vehicle with four passengers and vacation luggage weighs significantly more than it does during a solo commute. That extra weight affects braking distance, acceleration, cornering, ground clearance, and the load on the tires and suspension. Check the Gross Vehicle Weight Rating (GVWR) on the driver's door jamb sticker and do not exceed it. The GVWR includes the vehicle itself, all passengers, all cargo, and any trailer tongue weight.

If you are towing, the combined weight of the trailer and its contents must not exceed the vehicle's tow rating. The trailer tongue weight, typically 10% to 15% of the total trailer weight, adds directly to the vehicle's load and must be counted toward the GVWR. An overloaded vehicle overworks the engine, overheats the transmission, increases braking distance, and stresses the tires beyond their load rating.

Tire pressure for a loaded vehicle is often different from the pressure for unloaded driving. Many door jamb stickers list both. Use the loaded pressure when the vehicle is carrying a full complement of passengers and cargo.

Driving hours and fatigue

The recommended maximum driving day for a solo driver is 8 to 10 hours, with a break every 2 hours. This is not an arbitrary guideline. Reaction times degrade measurably after 2 hours of continuous driving, and significantly after 4 hours. Fatigue-related crashes on summer road trips are common because drivers overestimate their endurance and underestimate how much attention sustained highway driving consumes.

Plan your route with scheduled stops. Fuel stops, meal stops, and short walking breaks serve double duty: they refuel you and the vehicle, and they provide natural checkpoints to assess how you are feeling. If you are drowsy, stop driving. A 20-minute nap at a rest area is more effective than caffeine and vastly safer than pushing through.

Share driving responsibilities. Two drivers who each drive 4 to 5 hours arrive rested and alert. One driver who drives 10 hours arrives exhausted and impaired.

Carry water and supplies

A breakdown in summer heat is a medical situation as well as a mechanical one. Carry at least one gallon of drinking water per person per day for the length of your trip, plus extra engine coolant and a gallon of plain water for emergency cooling system refills. Your year-round vehicle emergency kit should already include these items, but verify the water supply is fresh and the coolant container has not leaked before departure.

Summer hazards

Sun glare, wildlife, and road surface heat

Sun glare

The sun's low angle during the first and last hours of daylight creates direct glare that can reduce visibility to near zero. Eastbound morning commuters and westbound evening commuters face this daily during summer. The glare is worst when the windshield is dirty, because dust, oil film, and smudges scatter the light across the entire field of view.

Keep the inside of the windshield clean. The outside gets attention from car washes and washer fluid, but the inside collects a film from interior off-gassing that is invisible until sunlight hits it at the wrong angle. Clean it with glass cleaner and a microfiber cloth at least monthly. Keep a pair of polarized sunglasses in the vehicle. Polarized lenses reduce glare from reflected surfaces more effectively than standard tinted lenses. Use the visor, but be aware that the visor blocks your view of traffic signals when positioned for low-angle glare. Slow down when you cannot see clearly. If the glare is blinding and you cannot see the road or traffic ahead, find a safe place to pull over and wait a few minutes for the sun's angle to change.

Wildlife crossings

Wildlife-vehicle collisions peak during two periods: the autumn mating season (October through December for deer) and the summer activity season (May through August), when long daylight hours mean more animal movement and young animals are dispersing from their birth areas. According to FHWA, there are an estimated one to two million wildlife-vehicle collisions annually in the United States, causing approximately 200 human fatalities and over 26,000 injuries per year.

Dawn and dusk are the highest-risk times because deer, elk, moose, and many other large animals are crepuscular, most active during twilight hours. Summer driving at dawn and dusk through rural areas, near forests, along rivers and streams, and through areas with wildlife-crossing signs requires heightened scanning beyond the normal driving sight distance.

If a large animal is in or near the road, brake firmly in your lane. Do not swerve. Swerving to avoid a deer at highway speed frequently causes a more serious crash than hitting the animal, including rollovers, departures from the road into trees or ditches, and head-on collisions with oncoming traffic. Brake as hard as you safely can while maintaining control, but keep the vehicle in your lane.

If you see one deer, expect more. Deer travel in groups. The animal that crossed the road safely is often followed by one or two more that are harder to see.

Construction season

Summer is peak construction season on American highways. More projects are active, more lanes are closed, and more workers are on foot near travel lanes than at any other time of year. According to FHWA, construction zone crashes cause approximately 700 to 800 fatalities annually, and the majority of victims are drivers and passengers, not workers. The combination of summer traffic volumes, vacation driving, and unfamiliar routes through construction zones creates conditions where rear-end collisions and lane-departure crashes spike.

Summer construction zones are hotter than the surrounding road. Temporary asphalt, dark surfaces without shade trees, and stop-and-go traffic in zones with no airflow create conditions where engine overheating and driver heat exhaustion compound the navigational hazards of the construction zone itself. Keep water accessible, run the A/C before entering the zone so the cabin is cool, and be prepared for extended delays in heavy traffic during summer weekends.

If you are planning a long summer road trip, check state DOT websites for active construction projects along your route. Many states maintain interactive maps showing lane closures, expected delays, and alternate routes. Adjusting your departure time or route to avoid major construction zones can save hours and significantly reduce stress. For detailed guidance on navigating construction zones, see our Adverse Conditions guide.

Road surface heat effects

Asphalt softens in extreme heat. On the hottest days, you may notice the road surface feels different under the tires, slightly softer or stickier. In extreme cases, particularly on older road surfaces, the binder material can bleed to the surface, creating patches of dark, tacky material that can be slippery. This is most common on secondary roads and rural highways that have not been recently resurfaced.

Heat mirages, the shimmering pools of apparent water on the road ahead, are a visual distraction but not a driving hazard. They are caused by a layer of superheated air just above the road surface bending light. The effect disappears as you approach. Do not brake or swerve for a heat mirage.

When you are stranded

Roadside breakdown in summer heat

A breakdown in winter means cold. A breakdown in summer means heat, and heat can become a medical emergency faster than most people expect. A vehicle parked on the shoulder of a highway in direct summer sun with no shade and no air conditioning is a hostile environment for human occupants, especially for children, elderly passengers, and pets.

Priorities during a summer breakdown

Get out of the vehicle if it is safe to do so. Unlike winter, where the vehicle is shelter, in summer the vehicle's interior becomes dangerously hot once the engine and A/C are off. If you can safely exit the vehicle and move to a shaded area away from traffic, do so. If the only option is the shoulder of a busy highway with no shade, stay in the vehicle with windows down rather than standing next to the travel lanes.

Drink water. Dehydration in heat begins quickly and accelerates performance decline. Drink the water in your vehicle emergency kit. Do not ration it. If help is on the way, staying hydrated is the priority. Symptoms of heat exhaustion include heavy sweating, weakness, nausea, dizziness, and headache. If symptoms progress to confusion, cessation of sweating, or loss of consciousness, that is heat stroke, a life-threatening emergency. Call 911.

Create shade if none exists. A sun shade for the windshield, a blanket draped between the open doors, or even a jacket hung from the vehicle provides modest relief from direct sun. If you are changing a tire on a hot day, work on the shaded side of the vehicle if possible, and take breaks in shade to avoid heat exhaustion.

Protect vulnerable passengers. Children, elderly passengers, and anyone with a medical condition should be moved to shade first. Wet a cloth with water and apply it to the neck and forehead for evaporative cooling. Do not leave anyone in a closed vehicle while you go for help.

Summer additions to the vehicle kit

Your year-round vehicle emergency kit should already include water, a first aid kit, and basic tools. For summer, add or verify: extra water beyond the baseline, a collapsible sun shade for the windshield, sunscreen, a wide-brimmed hat, extra engine coolant, and a spray bottle for misting water on skin for evaporative cooling. If you travel through desert or remote areas, carry more water than you think you need. The general guideline for hot-weather travel is one gallon per person per day plus a gallon for the radiator.

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