Flash flood warnings triggered by heavy rain were issued several times in August for the Big Rock Fire burn scar spanning Jefferson and Madison counties in southeastern Idaho. On August 22, the National Weather Service office in Pocatello also issued a flash flood warning for thunderstorms crossing the Big Rock burn scar near Hays.
Areas Affected
The Big Rock Fire escaped containment lines in early August and prompted mandatory evacuations. The burn scar left behind has since contributed to the flash flood threat. According to the National Weather Service, rainfall of 0.25 to 0.5 inches per hour on slopes stripped of vegetation can quickly send debris flows of rocks, mud, and tree fragments down drainages. Low-lying roads, including those in Hays, have been closed as a precaution by Jefferson and Madison counties whenever heavy rain falls.
What RV Travelers Need to Know
Those planning to use campgrounds or roads near the Big Rock burn scar should check the National Weather Service Pocatello warning page frequently. If a flash flood warning is issued, leave drainages and low-lying areas immediately for higher ground. Debris-flow hazards can persist for several hours after rain ends, so it is safer to take an alternate route until officials announce that roads have reopened. Because thunderstorms are frequent in the evening, travelers may also want to allow extra time for nighttime driving or arrival at a campground.
Photo: Alessandro Verniani / Original photo. CC BY-SA 4.0. Photo date: 2026-10-15 13:41:28.
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