September 4, 2026

No severe thunderstorm or excessive rainfall risk area covers the region today. Alaska holds five active National Weather Service alerts this morning, Idaho three, and Oregon two. Washington does not appear among the states carrying land based alerts.

The Pacific Northwest sits under building upper level ridging, which through early September usually means warm, dry, and stable conditions rather than storms. That is comfortable weather and it is also fire weather, which is the region's actual variable this month.

The earthquake sequence in the Fox Islands is the region's ongoing item and it grew stronger since yesterday. United States Geological Survey records show a magnitude 6.3 about 84 kilometers southwest of Nikolski, Alaska at 11:17 UTC on September 3, followed by a magnitude 5.2 seven minutes later, another magnitude 5.2 at 13:03, a magnitude 5.3 at 18:45, and a magnitude 5.5 about 100 kilometers south of Nikolski at 20:21. Earlier events in the same sequence ran from September 1. A magnitude 5.0 occurred about 236 kilometers east-southeast of Attu Station on September 4.

The Tsunami Warning Centers state that there is no tsunami warning, advisory, watch, or threat in effect. The most recent message from them is a tsunami information statement issued for the magnitude 5.2 event on September 3, and an information statement is the lowest category: it says an earthquake occurred and that no action is required. Nikolski is a small community on Umnak Island and the sequence is offshore of it.

What this means for households on the Alaska coast is what it always means. A sequence like this is a reminder rather than a warning. The rule that matters is not on a website: if you are near the coast and the ground shakes hard enough that it is difficult to stand, move inland or uphill immediately without waiting for an official message, because a locally generated wave can arrive before any message does. For a distant earthquake, the official message is the guide and there is no such message in effect now.

Wildfire is the region's other standing item. In Washington, the Little Giant fire stands at 170,784 acres and 49 percent contained, and the Sinlahekin fire at 166,330 acres and 38 percent contained. In Oregon, the Big Grass fire in the Vale District is at 578,637 acres and 94 percent contained, the Rowe Creek Complex near Prineville at 373,927 acres and 96 percent, and the Grasshopper fire on the Mount Hood National Forest at 93,972 acres and 83 percent. Nationally the wildfire preparedness level stands at 5, its highest step, with 84 large uncontained fires and 20,245 personnel assigned. The year to date total is 52,626 fires and 8,265,751 acres, which is 126 percent of the ten year average for fires and 163 percent for acres. Those figures come from the National Interagency Fire Center report dated September 2, so they are one to two days behind this morning.

The direction of travel in Oregon is good: three large fires there are now above 80 percent containment. Washington's two are the ones with the most work left.

Smoke is the health item most likely to affect households here, and it moves with the wind rather than with the fire. An air quality advisory issued for parts of Oregon in late August was written to run through early September; its current status could not be confirmed this run, so this brief does not assert that it is either still in force or expired. AirNow gives a current reading for your address, which is more useful than any advisory's status.

No other public health advisories specific to the Northwest were confirmed this run. The Centers for Disease Control and Prevention's Health Alert Network archive could not be read this run, so this brief makes no claim about national health advisories in either direction.

September and early October are usually the weeks when the Northwest fire season either ends or does not, and the hinge is rain. Building ridging keeps the region warm and dry in the near term, and the Weather Prediction Center's medium range guidance puts the next organized moisture into the northern Rockies late this weekend into early next week rather than onto the Cascades.

For households near active fire, containment percentages are the number worth watching and the one most often misread. A fire at 49 percent contained is not half out. Containment describes the share of the perimeter that crews expect to hold, and the uncontained share is where growth happens. Two fires in Washington at 38 and 49 percent are the ones with room to move if wind arrives.

The practical version for anyone in an evacuation zone is the same as it was in July and worth repeating because people relax in September. Know your zone and your two ways out. Keep the vehicle above half a tank. Keep the documents that are hard to replace in one place you can pick up on the way to the car. If you have livestock or animals, the plan for them takes longer than the plan for you and should already be written down.

On the seismic side, the useful takeaway from a week like this one is that it is a reason to check something rather than to worry about something. Water is the item that runs out first after a strong earthquake, and a household that has several days of it stored has bought itself the thing that is hardest to improvise. Securing a water heater and the tall furniture in bedrooms is a Saturday afternoon and it works.