Dangerous fire weather conditions have continued to plague portions of the Pacific Northwest and Northern Great Basin in September, with the National Weather Service issuing multiple Red Flag Warnings across Oregon and Idaho as the season presses toward its close.

Recent Red Flag Events

On September 17, the National Weather Service office in Boise issued a Red Flag Warning covering the Northern Boise National Forest and Southern Boise/Western Sawtooth National Forest, including the Camas Prairie. Conditions driving the warning included critically low relative humidity, temperatures in the mid-to-upper 80s, and erratic gusty winds.

Simultaneously, NWS Portland issued a Severe Red Flag Warning for several Eastern Oregon fire weather zones, including:

  • Fire Weather Zone 670 — Burns BLM
  • Fire Weather Zone 671 — Steens Mountain
  • Fire Weather Zone 674 — Northwestern Vale BLM
  • Fire Weather Zone 675 — Baker Valley

An associated Fire Weather Watch was also posted for parts of Idaho as a low-pressure system moved through southeastern Oregon into southwestern Idaho, bringing the potential for dry lightning — thunderstorms that produce lightning with little or no rainfall reaching the ground.

Why Late September Remains Dangerous

Many residents assume wildfire danger diminishes as summer fades. Fire meteorologists at the Northwest Interagency Coordination Center (NWCC) consistently warn otherwise. Several factors keep fire risk elevated through late September east of the Cascades:

  • Critically dry fuels: Grasses, shrubs, and forest understories that baked all summer carry very low fuel moisture content well into fall.
  • Offshore flow events: When high pressure builds east of the Cascades and a low sits offshore, strong easterly winds drive extremely low humidity into west-side communities. These "east wind" events have ignited and rapidly spread some of the region's most destructive fires.
  • Late-season thunderstorms: Fall storm systems that lack sufficient moisture can produce dry lightning across elevated terrain, igniting new fires when suppression resources are stretched thin.
  • Reduced overnight recovery: While nights get longer in fall, relative humidity does not always recover sufficiently to allow fire behavior to slow.

Weekly Outlook

The latest wildfire outlook from the Northwest Predictive Services notes that the Pacific Northwest climbs back to above-normal fire potential as early fall rain patterns clear and fuels continue to dry out east of the Cascades. The Northern Rockies, by contrast, are seeing cooler and wetter conditions as maritime systems push into Montana and Idaho, which may moderate risk in those zones.

Residents in Eastern Oregon, Eastern Washington, and southern Idaho should monitor NWS Red Flag Warnings closely. Any outdoor burning — even where not prohibited — carries extreme risk under dry and windy conditions. Report smoke or new fire starts to 911 immediately.