A strong atmospheric river is forecast to bring periods of heavy rain to northwest Oregon and southwest Washington from Thursday, December 18 through Saturday, December 20, 2025, prompting a Flood Watch from the Portland weather bureau.

What Is Expected

According to the Portland weather bureau, a moderate to strong atmospheric river will move across the region Tuesday through Saturday, dropping widespread heavy rain onto already saturated soils and elevated rivers. The bureau notes that the heaviest rainfall is expected on Thursday, increasing the risk of flooding in vulnerable locations.

Areas Included

The Flood Watch covers all locations in northwest Oregon and southwest Washington under the Portland weather bureau’s area of responsibility. This includes coastal communities, interior valleys, foothills, and mountain drainages where runoff from the Coast Range, Willapa Hills, and Cascades can quickly swell rivers and creeks.

Potential Impacts

Forecasters warn that flooding is expected Thursday in poor-drainage locations, urban areas, and other flood‑prone spots. Landslides in steep terrain and debris flows near recently burned areas are possible at any time during this wet period, and river flooding is most likely from Thursday night into Friday as runoff works downstream.

How to Prepare

The Portland weather bureau urges people living in historically flood‑impacted neighborhoods to review their flood plans now and take steps to protect homes, belongings, and vehicles before the heaviest rain arrives. Drivers are reminded not to enter flooded roads and to find alternate routes, since even shallow water can be dangerous.

Where to Get More Information

Residents should stay tuned to the Portland weather bureau’s forecasts and updates as the event unfolds. Additional safety guidance and flood-readiness information is available at the bureau’s flood safety webpage at

Http:// weather.gov/safety/flood.