NWS Boise IDFF.W 0013September 18, 2026
Flash Flood Warning: Boise, ID
The National Weather Service office in Boise issued a flash flood warning for Boise in Idaho, which was in force until 8:15 p.m. local time on September 18. It was the 13th flash flood warning the NWS office in Boise issued in 2026. Idaho had 10 flash flood warnings in September 2026, against 3 in an average September of 2008-2025 (Idaho's flash flood warnings by year).
ExpiredWarning
In force for 2.5 hours; it has expired. The agency may have replaced it with a new notice.
The notice
- Issued by
- National Weather Service, Boise ID
- Area
- Boise
- State
- Idaho
- Level
- Warning
- Issued
- 5:47 p.m. MDT, September 18, 2026
- Expires
- 8:15 p.m. MDT, September 18, 2026
- CAP severity, certainty, urgency
- Severe, Likely, Immediate
- VTEC event
- KBOI FF.W 0013
- Official source
- National Weather Service: the notice at its source
Source: National Weather Service: the notice at its source. AreaZine rebuilds this page from the agency's record; the agency's page is the one to act on. A U.S. Government work, in the public domain.
The notice as issued
FFWBOI The National Weather Service in Boise has issued a * Flash Flood Warning for... The Wapiti Burn Area in... Northeastern Boise County in southwestern Idaho... * Until 815 PM MDT. * At 547 PM MDT, emergency management reported thunderstorms producing heavy rain over the Wapiti Burn Area. Flash flooding is ongoing or expected to begin shortly. Excessive rainfall over the burn scar will result in debris flow moving through the High Drainage Test. The debris flow can consist of rock, mud, vegetation and other loose materials. HAZARD...Life threatening flash flooding and debris flows in and around the Wapiti Fire Burn Scar. SOURCE...Emergency management reported debris on Idaho State Highway 21 between mileposts 103 and 105. IMPACT...Life threatening flash flooding and debris flows in and around the Wapiti Fire Burn Scar will impact Grandjean Road and Highway 21 from east of Lowman to Banner Summit. * Some locations that will experience flash flooding include... Grandjean.
What the agency told people to do
This is a life threatening situation. Heavy rainfall will cause extensive and severe flash flooding of creeks...streams...and ditches in the Wapiti Burn Area. Severe debris flows can also be anticipated across roads. Roads and driveways may be washed away in places. If you encounter flood waters...climb to safety.
Source: National Weather Service: the notice at its source. The text is the agency's, unedited. A U.S. Government work, in the public domain.