textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Continued hot, dry, and smoky into Tuesday.

- Breezy afternoon winds through Tuesday.

- Gradual cooling through the week.

- Increasing chance of showers and thunderstorms Wednesday and beyond, especially on the Idaho side.

SHORT TERM /Through Tuesday Night/

Issued 200 PM MDT SUN AUG 9 2026 Hot, dry, smoky weather will continue through Tuesday, although not as hot as previous days as high pressure aloft gradually weakens over the Great Basin. Southern Twin Falls County will remain on the northern fringe of monsoon moisture with isolated thunderstorms late today and again late Monday. Westerly winds aloft will change to southwesterly Tuesday as an upper trough deepens off the northwest coast. This change will allow monsoon moisture to move northward across the NV/ID border for a 15-20% chance of showers and thunderstorms late Tuesday, continuing in Twin Falls County Tuesday night. Smoke continues to stream across our CWA mainly from the Big Grass fire (in southern Malheur County and western Owyhee County), and from the Wright Springs fire in south-central Oregon. Latest RRFS model forecasts less smoke in our CWA by Tuesday but confidence is low.

LONG TERM /Wednesday through Sunday/

Issued 200 PM MDT SUN AUG 9 2026 High pressure will build over the Desert Southwest as a weak trough moves into the West Coast on Wednesday. This will bring southwest flow over the region, which will cool temperatures slightly, as the high pressure center shifts further east. Monsoonal moisture will advect northward, but long range models keep the best chances of associated showers and thunderstorms to our south and east through Thursday. By Friday, models substantially increase precipitation coverage over high terrain through the weekend. The Central Idaho Mountains and high terrain along the Nevada border will see the best chance for showers and thunderstorms (20-40% chance). Warm and breezy conditions will continue through the weekend, with temperatures slightly below normal through the weekend. High temperatures in the valleys will range from the mid to upper 80s through Saturday, with high temperatures in the mountains in the mid to upper 70s.

AVIATION /00Z Monday through Tuesday/

Issued 533 PM MDT SUN AUG 9 2026 Generally VFR with periods of MVFR conditions possible mainly near KONO-KEUL in thicker wildfire smoke this evening through Monday morning. Mountains obscured in smoke. High density altitude from heat through sunset. Surface winds: W-NW 5-10 kt, variable less than 10 kt overnight. Winds aloft at 10kft: W-SW 10-20 kt.

KBOI...General improvement to VFR conditions. Foothills still obscured in smoke. High density altitude from heat continuing through sunset. Surface winds: NW 6-8 kt, becoming variable less than 6 kt overnight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Air Quality Alert until 1 PM MDT Monday for IDZ011>015-028-029- 033. OR...Air Quality Alert until 1 PM MDT /noon PDT/ Monday for ORZ061>064.