Red Flag Warnings Blanket Five Northern Rockies and Plains States
Critical fire weather triggered Red Flag Warnings across Montana, Wyoming, Idaho, and the Dakotas on Sept. 10, capping an active season in the region.
The National Weather Service issued Red Flag Warnings across parts of Montana, Wyoming, North Dakota, South Dakota and Idaho on Sept. 10. Seven NWS offices (Billings, Bismarck, Riverton, Glasgow, Cheyenne, Pocatello and Missoula) warned of critical fire-weather conditions, in which any fire that started could spread rapidly, The Watchers reported.
What triggered the warnings
Forecasters expected westerly winds of about 15–25 mph with gusts to 40 mph in some areas, and relative humidity dropping to 10–20% across most of the warned zones. The driest air was in southeastern Wyoming, where minimum humidity could fall to 5%. Some warnings started at noon, and most expired between 8 and 9 p.m. MDT that evening.
Among the areas named in the warnings:
- Montana: Golden Valley, Musselshell and Park counties
- Wyoming: Sweetwater and Fremont counties, plus the Sierra Madre and Snowy ranges
- Idaho: the Upper Snake River Valley
Warning details as of Sept. 10, 2026.
What a Red Flag Warning means
A Red Flag Warning doesn’t mean a fire is burning. It means the weather (wind, low humidity and dry fuels together) is at the point where a new ignition can grow faster than crews can catch it. During a warning:
- Don’t burn debris or yard waste, even if you have a permit.
- Keep vehicles off dry grass. Hot exhaust and dragging chains start roadside fires.
- Put off mowing, welding and grinding outdoors.
- Check your county’s emergency-alert sign-up so evacuation notices reach you.
FireVerge’s red flag warnings map page explains how to find current warnings for your area.
A busy season in southwest Montana
The warnings came during an active season in the region. In mid-August, the Sand Creek Fire about 7.5 miles southeast of Wisdom, near Maverick Mountain, had grown to 31,652 acres at 1% containment. It threatened more than 170 homes and other infrastructure, including commercial buildings, utilities and communications sites, NBC Montana reported on Aug. 17. The fire is on the Beaverhead-Deerlodge National Forest, and FEMA approved a Fire Management Assistance Grant to help cover its costs.
For longer-term context on the region, see FireVerge’s Montana and Wyoming state pages.