The National Weather Service office in Pocatello issued a Red Flag Warning Monday afternoon covering large portions of southeastern Idaho, including the Idaho Falls area, with the warning running from noon through 9:00 PM MDT Tuesday, June 16.
The warning encompasses four fire weather zones across the region: Zone 410, which covers the Upper Snake River Valley and Idaho Falls Bureau of Land Management lands; Zone 413, the Caribou Range and Caribou National Forest; Zone 425, the Middle Snake River Valley and Twin Falls BLM lands north of the Snake River; and Zone 427, the Goose Creek and Raft River Valley area, including portions of the Southern Sawtooth National Forest and Twin Falls BLM lands south of the Snake River.
What Triggers a Red Flag Warning
A Red Flag Warning signals a combination of weather conditions that dramatically elevate the risk of wildfire ignition and rapid fire spread. The National Weather Service activates the warning when relative humidity drops to 15 percent or below, paired with wind gusts reaching at least 25 miles per hour in mountainous terrain or 30 miles per hour across the Snake River Plain.
Thunderstorm activity also factors into the criteria. When thunderstorm coverage reaches 25 percent or more without meeting specific rainfall thresholds, the elevated lightning risk combined with dry vegetation and gusty winds creates dangerous fire weather conditions even without meeting the humidity and wind benchmarks separately.
The combination of low humidity, dried-out vegetation from warmer summer temperatures, and strong gusty winds means any spark — whether from a lightning strike, a vehicle, outdoor burning, or equipment — can rapidly grow into a fast-moving wildfire with little warning.
What Residents and Outdoor Users Should Know
Bonneville County residents, outdoor recreationists, and anyone traveling through the affected fire weather zones should take the warning seriously for the duration of Tuesday. Conditions favorable for rapid fire spread are expected to be most pronounced during the afternoon and evening hours, when temperatures peak and humidity typically reaches its lowest point of the day.
State and federal land managers typically ask the public to avoid activities that could ignite fires during Red Flag Warning periods. This includes outdoor burning, operating equipment that can throw sparks, parking vehicles in dry grass, and using fireworks or any open flame in fire-prone areas.
Campers and hikers in the Caribou National Forest and BLM lands within the affected zones should be aware of rapidly changing fire conditions and know their exit routes. Anyone who spots a wildfire in a remote area is urged to report it immediately by calling 911.
Motorists on Highway 20 and Interstate 15 corridors through southeastern Idaho should also remain alert to any smoke or fire activity, particularly in areas where dry grass and brush border the roadways. Wildland fires can cross highways quickly under red flag conditions.
What Comes Next
The Red Flag Warning is set to expire at 9:00 PM MDT Tuesday, June 16. Residents should monitor updates from the National Weather Service Pocatello as conditions evolve, particularly if thunderstorm activity increases over the mountain ranges. Weather conditions can shift quickly during summer afternoons in southeastern Idaho, and additional watches or warnings may be issued if fire weather conditions persist or worsen into Wednesday.
Bonneville County Emergency Management and the Idaho Department of Lands coordinate with federal partners during elevated fire weather periods. Residents are encouraged to sign up for local emergency alerts and keep aware of any fire restrictions currently in effect on public lands in and around Bonneville County. The public should also maintain defensible space around homes and structures and ensure any outdoor fire equipment or burning debris is fully extinguished before and during any Red Flag Warning period.