Flood in Upper Koyukuk Valley, Alaska

Flood August 28, 2025 – August 31, 2025 · Upper Koyukuk Valley, Alaska

Where the report was made, with tornadoes recorded within 15 miles over the years.

What the National Weather Service wrote

Emergency management personnel with the Tanana Chiefs Conference and local officials from Allakaket reported a prolonged moderate to major flood that surrounded most of the lower community, Old Town, and the old runway. Several roads including the airport access road and Main Street washed out. The river officially crested at 64.54 feet on August 31st.

The wider storm

A prolonged period of deep moist southwesterly flow from the North Pacific ocean, otherwise known as an Atmospheric River, produced several days of heavy rainfall along the south slopes of the Brooks Range. Over about a 5 day period total rainfall of three to six inches resulted in considerable flooding for the Koyukuk and it's tributaries. In addition this southwest flow also resulted in very strong winds through the Alaska Range passes.

Began near Allakaket (66.5494, -152.6848).

Source: NOAA Storm Events Database, event 1293180. Narratives are written by the National Weather Service forecast office that issued the report.

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