Fire weather danger expanded sharply across the western United States Monday, with the National Weather Service placing 21 active Red Flag Warnings across nine states — Colorado, Idaho, Nebraska, New Mexico, Oregon, South Dakota, Utah, Washington, and Wyoming. That is more than triple the six alerts that covered four states Sunday, when warnings were concentrated in Minnesota, Nebraska, Wyoming, and Alaska.
The expansion marks a broad westward and southward surge. Areas newly under warnings include Utah’s Color Country Mountains, Western Uintah Basin, Manti National Forest, San Rafael Swell, and Central Utah Mountains; New Mexico’s Middle Rio Grande Valley, North Central Mountains, Sandia and Manzano Mountains, and Central Highlands; and Washington’s Okanogan Valley, Methow Valley, Central Washington Cascade Foothills, Waterville Plateau, and the Eastern Columbia Basin stretching toward Spokane. In the Northern Plains, the South Dakota Badlands, Pine Ridge, Fall River County, and Bennett County areas remain under warnings alongside Wyoming’s Weston County Plains and Natrona County — including the Casper area.
Wind and critically low relative humidity are the twin drivers. The National Weather Service in Salt Lake City cited west to northwest winds of 10 to 20 mph with gusts to 30 mph through Tuesday evening, with warnings running from noon Tuesday through 9 PM MDT Wednesday for much of Utah. In the Northern Plains, the National Weather Service warned that relative humidity across northeastern Wyoming and far southwestern South Dakota will drop to near 15 percent, with some warnings there expiring as early as 8 PM MDT Tuesday.
The duration and breadth of this event set it apart from Sunday’s outbreak. Multiple NWS offices — Salt Lake City, Albuquerque, Spokane, and others — are issuing concurrent warnings, meaning fire managers across distinct geographic regions face elevated risk simultaneously. The combination of dry continental air pushing south and west, terrain-channeled winds, and minimal vegetation moisture creates conditions the National Weather Service describes as capable of producing extreme fire behavior.
A Red Flag Warning, as defined by the National Weather Service, signals that critical fire weather conditions are either occurring or imminent. With 21 warnings active from the Rio Grande Valley to the Cascade foothills and the Badlands, Monday marks one of the more geographically extensive fire-weather events so far this season. Forecasters have not yet indicated when the pattern will relax across the full nine-state footprint.