Extreme Heat, Dry Thunderstorms, and Red Flag Warnings Fuel Fire Danger Across the Northwest

A persistent high-pressure ridge anchored over the Pacific Northwest and Intermountain West is driving extreme fire weather conditions across the region this week, with Red Flag Warnings active across portions of Oregon and elevated fire danger stretching through central and eastern Washington, Idaho, and the Northern Rockies. Forecasters warn that the combination of record-level heat, critically low humidity, gusty winds, and scattered dry thunderstorms creates the highest-risk fire weather conditions of the season so far.

Red Flag Warning: South-Central Oregon

The National Weather Service has issued Red Flag Warnings for south-central Oregon, where the confluence of above-normal temperatures, afternoon relative humidities of just 5–15 percent, and southwest-to-west winds of 12–22 mph with gusts reaching 30 mph are creating extreme fire behavior potential. Any new ignition under these conditions can grow to significant size within minutes.

Fire Weather Watch: Columbia Basin

A Fire Weather Watch has been issued for portions of the Columbia Basin, signaling that Red Flag conditions may develop in the coming days if forecasted weather patterns materialize. The Columbia Basin — a broad, flat expanse of grass and shrub-steppe terrain spanning south-central Washington into northern Oregon — is highly susceptible to fast-moving fire events, as demonstrated by the Ryegrass Coulee Fire near Vantage earlier this week.

Dry Thunderstorms East of the Cascades

Monsoonal moisture working northward from Mexico is bringing an additional threat: dry thunderstorms east of the Cascades. These storms produce lightning but little or no rainfall, as precipitation evaporates before reaching the ground in the hot, dry lower atmosphere. Each dry lightning strike represents a potential new ignition on terrain that is already critically dry after weeks of above-normal temperatures. Warm Springs Reservation and the Columbia Basin area are among the areas most susceptible to dry lightning ignitions this week.

Extreme Heat Through Mid-July

NIFC meteorologists are forecasting extreme heat over the lower elevations of the Intermountain West and Northern Great Plains through the middle of July. The sustained heat has desiccated fine fuels — grasses, shrubs, and needle litter — to critically low moisture contents, where they ignite easily and carry fire at exceptional rates of spread. Live fuel moisture in some areas of southeastern Oregon and southern Idaho has fallen to levels typically seen at the peak of fire season in late August.

What Firefighters Are Watching

Fire weather forecasters track several key indicators during high-risk periods:

Relative Humidity (RH): Values below 15% create critical fire conditions; the Pacific Northwest is seeing 5–15% RH regularly this week.
Wind speed and direction: Winds above 20 mph can double or triple a fire's rate of spread; gusty, erratic winds create dangerous spotting conditions.
Temperature: Each 10-degree temperature increase roughly doubles the rate of fire spread in grass fuels.
Haines Index: A measure of the potential for large fire development based on lower atmosphere stability and dryness. The Northwest is seeing high Haines Index values this week.