Boise, Idaho – A surge of tropical moisture is setting the stage for dangerous flash flooding across southwest and central Idaho through Thursday, with up to 1.7 inches of rain expected in mountain communities and urban centers alike.
According to the National Weather Service in Boise, an unusually moist air mass for late August is fueling daily rounds of showers and thunderstorms. A Flash Flood Watch remains in effect for the entire Treasure Valley, Snake River Plain, and central mountains through early Friday. Heaviest rainfall totals are forecast near Stanley, Lowman, and Idaho City, where over 1.5 inches of rain may fall.
Boise and Twin Falls could see around half an inch, with isolated higher totals in thunderstorms. McCall, Hailey, and Fairfield are also in the zone for significant downpours, with 1 to 1.2 inches possible. Urban runoff, saturated soils, and steep terrain increase the risk of sudden flooding, especially along U.S. 20, U.S. 95, and Highway 21.
Residents are urged to avoid flooded roadways, monitor local alerts, and have an evacuation plan ready in vulnerable areas.
Storm chances persist each day through Thursday night, with additional advisories possible as rainfall continues to accumulate.
