Critical Fire Weather Returns: Southwest Winds and Single-Digit Humidity Extend Danger Across Oregon and Washington

Fire weather across the Pacific Northwest continues to present serious challenges for firefighting crews and communities as the region moves into the Labor Day holiday weekend. Southwest winds of 15 to 25 mph with gusts up to 35 mph are combining with unseasonably warm temperatures and relative humidity levels dropping into the critical 9 to 19 percent range — conditions that fuel rapid fire spread and can quickly overwhelm containment efforts on active incidents.

Red Flag Warnings in Central Washington

Red Flag Warnings have been in effect across central Washington, with gusty afternoon winds, high temperatures in the mid-80s to mid-90s Fahrenheit, and humidity values in the single digits to low 20s extending the elevated-to-critical fire threat across eastern Washington and into the northern Rockies. These conditions closely mirror those that drove the catastrophic Spokane Complex and other early-August fire runs that devastated communities throughout the region.

On August 1, the Storm Prediction Center issued a rare Extremely Critical Risk in its Day 1 Fire Weather Outlook, encompassing the majority of eastern Washington — one of the strongest fire weather statements ever issued for the Pacific Northwest. That event also saw the first-ever Particularly Dangerous Situation (PDS) Red Flag Warning issued in the region, reflecting the unprecedented nature of the atmospheric setup.

Northern Rockies Face Extreme Gusts

Across the broader Northwest region and into the northern Rockies, conditions are even more severe. Gusts up to 45 to 50 mph are possible across parts of the northern Rockies, with breezy westerly winds of 15-25 mph and gusts of 25-35 mph expected broadly across the Intermountain West. Relative humidity ranging from just 5 to 25% — with the lower end of that range across interior portions — creates conditions in which any ignition can rapidly become a large fire.

Oregon's Fuels Are Critically Dry

Vegetation across large portions of Oregon remains exceptionally dry following widespread drought, historically low winter snowpack, and a summer dominated by record heat. Fire behavior analysts note that both fine fuels (grasses and brush) and heavy fuels (logs and large wood) are at critically low moisture levels in many parts of the state — a combination that supports both rapid fire spread across grass-covered terrain and intense, long-duration burning in timber country.

The Bureau of Land Management Burns District and the Oregon Division of State Lands issued an emergency fire prevention order on August 26 prohibiting open flames, campfires, debris burns, and fireworks in response to these fuel conditions. Similar prevention orders are in effect across multiple national forests throughout Oregon and Washington.

Lightning Threat Adds to Concern

Forecasters are also monitoring the potential for dry thunderstorms — storms that produce lightning but little or no rain reaching the ground — to move through portions of the Great Basin and Pacific Northwest. Dry lightning has been responsible for many of this season's significant fire starts, including the lightning siege that ignited 16 separate fires in Baker County on a single day in late August. Any new dry lightning events could rapidly overwhelm already-stretched firefighting resources.

Outlook Through Labor Day Weekend

The National Interagency Fire Center's Predictive Services staff notes that above-normal fire potential is expected to continue through September across the Pacific Northwest, Great Basin, and northern Rockies. Temperatures are forecast to remain above seasonal norms, precipitation is not expected to provide meaningful relief, and fuel moisture levels show no signs of recovery in the near term.