textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Scattered showers and strong thunderstorms in south-central Idaho through this evening. Isolated showers and weaker thunderstorms elsewhere in western Idaho until sunset. Clearing in eastern Oregon.

- Gusty outflow winds up to 50 mph from thunderstorms in south- central Idaho through sunset.

- Dry and slightly cooler Sunday, then several degrees warmer again Monday with a chance of afternoon thunderstorms in southern areas.

SHORT TERM /Through Monday Night/

Issued 213 PM MDT SAT AUG 22 2026 At 1 PM MDT scattered showers and thunderstorms were already underway in Owyhee and Twin Falls Counties, moving northeast. These will increase in coverage the rest of the afternoon and early evening, particularly in eastern Owyhee and Twin Falls Counties where monsoon moisture still exists. Meanwhile, a Pacific cold front has developed a band of light rain showers and isolated thunderstorms in Baker and Malheur Counties. The front and the showers/storms will move eastward into Idaho this afternoon and evening and help enhance the thunderstorms in south-central Idaho. Cooler and drier air will come in from the west overnight and Sunday, but a slight chance of afternoon thunderstorms will develop again in Twin Falls County Sunday afternoon. Monday looks several degrees warmer again as an upper trough exits east, replaced by a weak upper ridge over Oregon. Mid-level moisture will again increase and lead to a 15 to 30 percent chance of afternoon and evening thunderstorms in southern areas, while northern areas stay dry with increasing clouds in the afternoon.

LONG TERM /Tuesday through Saturday/

Issued 213 PM MDT SAT AUG 22 2026 Troughing off the shore of Washington and Oregon will keep most monsoonal moisture east of our area. This will keep mostly dry conditions across the area, with a low chance (under 15%) of afternoon showers and thunderstorms across our far eastern zones. Otherwise, breezy conditions will set in with a slight cooling trend. Temperatures come Tuesday will be around 5-10 degrees above normal, cooling to near normal come Saturday.

AVIATION /00Z Sunday through Monday/

Issued 529 PM MDT SAT AUG 22 2026

VFR. Scattered showers and thunderstorms this afternoon. Coverage will continue this evening mainly in SW-Idaho. Thunder capable of brief heavy rain, hail, and erratic outflows to 40-50 kt. BLDU possible with outflows. High density altitude this afternoon due to heat. Surface winds outside of storms: Variable 5-15 kt, except SW 10-20 kt with gusts to 25-30 kt in E-Oregon through 03z. Winds aloft at 10kft MSL: S-SW 10-25 kt.

KBOI...VFR. A 20% chance of thunderstorms this afternoon into evening. Thunderstorms capable of brief heavy rain, hail, and outflows to 30-40 kt. BLDU possible in outflows. High density altitude this afternoon due to heat. Surface winds: NW-N 6-12 kt this afternoon, becoming SE 5-15 kt tonight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning until midnight MDT tonight for IDZ401>403-421- 424-426. OR... Red Flag Warning until 8 PM PDT this evening for ORZ670>672.