A split fire weather pattern is defining conditions across the Pacific Northwest this weekend, as a Pacific moisture system delivers important rainfall to high-elevation fire zones while the Columbia Basin and eastern Oregon remain in a comparatively dry pocket — a pattern that contributed to the rapid ignition and spread of the Second Street Fire near Benton City on Friday.

Beneficial Rainfall for the Cascades

The National Interagency Fire Center's September 25 weather report notes that more widespread rainfall is expected near and west of the Cascades in both Oregon and Washington, with wetting rain also moving into northern Idaho and western Montana. This moisture is providing significant relief for firefighters working on the larger Cascade mountain fires, including the Little Giant and Sisi fires in Washington's Okanogan-Wenatchee National Forest.

Recent rain and isolated snow at higher elevations have moderated fire behavior across the Cascade crest, with most mountain fires dropping to smoldering and creeping activity. Minimum relative humidity on mountain fires has recovered substantially, reducing the risk of dangerous fire runs.

Columbia Basin: Still Dry

The picture is different east of the mountains. The Columbia Basin is experiencing breezy westerly winds accompanied by relatively higher humidity — above 30% in many locations — with isolated to scattered showers, but these conditions have not been sufficient to prevent new fire starts in the dry grass and brush fuels that blanket the region.

The Second Street Fire near Benton City ignited in afternoon heating on Friday amid these Columbia Basin conditions, spreading rapidly through grass, brush, and urban interface fuels. The Yakima Valley and Columbia Basin are known for localized foehn wind effects that can rapidly lower humidity and accelerate fire spread even when broader regional conditions appear moderate.

Looking Ahead

The broader weather pattern through late September favors continued improvement across the Pacific Northwest fire zone. Forecast models show:

  • Continued rainfall west of the Cascades through the weekend
  • Gradually improving humidity across eastern Washington and Oregon as the weekend progresses
  • Cooler overnight temperatures aiding overnight relative humidity recovery
  • No red flag warnings currently active anywhere in Washington state
  • No significant heat or wind events forecast for the next 5-7 days

The arrival of fall weather patterns typically marks the transition out of the most dangerous fire conditions across the Pacific Northwest. The combination of shorter days, cooler temperatures, and increasing precipitation generally reduces fire risk through October, though dry warm spells can still produce dangerous conditions in October and even into November in some years.

Fire Restrictions Remain in Place

Despite the improved weather outlook, fire restrictions remain active across the region. Washington's statewide burn ban runs through September 30, prohibiting all outdoor open burning. Stage 1 fire restrictions are in place on federal lands across central Oregon. Residents are reminded that fires can still ignite and spread rapidly during brief dry and windy periods even in fall, and that all burn restrictions should be followed until officially lifted by the relevant land management agencies.

Fire weather forecasts for the Pacific Northwest are available from the National Weather Service offices in Seattle, Portland, Pendleton, and Spokane, as well as through the NIFC's predictive services program at nifc.gov.