Aug 26, 2025
Monsoonal moisture surged into the region over a three day period, the most intense of which was the 26th. High atmospheric moisture content combined with weak flow in a monsoonal pattern to produce very moist storms moving very slowly. Additionally, as terrain served as the main trigger for convection, storms would train over the same spots for much longer than normal. Precipitable water was at near record levels around 1.2 inches.
Source: NOAA National Weather Service Storm Events Database (event 1295088). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Boise County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.