textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Continued very hot through Saturday.

- Continued smoky through at least Sunday.

- Breezy afternoon winds Friday through Sunday.

- Slight chance of thunderstorms along the ID/NV Saturday and Sunday as high-level monsoon moisture advances northward.

SHORT TERM /Through Saturday Night/

Issued 201 PM MDT THU AUG 6 2026 Continued very hot through Saturday and also dry and smoky, as the main upper ridge over the Great Basin reaches maximum intensity. Friday should be the hottest day by a slight margin. A weak Pacific cold front and supporting upper trough will weaken the main upper ridge and bring gradual cooling beginning Saturday night. High level monsoon moisture will advance northward to the NV/ID border late Saturday after being kept well south the past two weeks. This moisture, together with the weak incoming cold front, will bring a slight chance of high- based thunderstorms to Owyhee and Twin Falls Counties late Saturday and Saturday night. Afternoon winds will be breezy, especially Saturday in southern zones, as the cold front approaches. Thunderstorm outflow gusts must also be considered near the NV/ID border late Saturday.

LONG TERM /Sunday through Thursday/

Issued 201 PM MDT THU AUG 6 2026 The gradual cooling will end Tuesday when temperatures are only 3 to 6 degrees above normal under dry zonal flow aloft. Flow will become southwesterly again Wednesday ahead of the next approaching north Pacific trough, and monsoon moisture will again advance northward to the NV/ID border, especially into and east of Twin Falls County. Thursday's forecast is less clear as the GFS brings the next cool upper trough inland while ECMWF completely eliminates it. We hope for better model consistency tonight or tomorrow. Either way, high temperatures should stay below 100 degrees even under southwest flow aloft, as the main upper ridge continues to slowly weaken and shift south.

AVIATION /00Z Friday through Saturday/

Issued 548 PM MDT THU AUG 6 2026

Wildfire smoke will continue to bring MVFR conditions overnight tonight with IFR conditions likely in KBNO-KBKE-KONO. Conditions will improve to VFR by late tomorrow morning. High density altitude each afternoon due to hot temperatures. Mountains obscured in smoke. Surface winds: variable overnight less than 10 kt, then WNW 5-15 kt by late morning. Winds aloft at 10kft: W-SW 10-20 kt.

KBOI...Smoke will settle overnight, bringing MVFR conditions to the terminal through the late morning. VFR conditions will likely return tomorrow afternoon as smoke slightly lifts in the valley. Foothills obscured in smoke. Surface winds: SE 3-6 kt overnight, then NW 6-10 kt by late morning.

Weekend Outlook...Areas of MVFR visibility and local mountain obscuration due to wildfire smoke, otherwise VFR. High density altitude each afternoon due to hot temperatures. A 15% chance of afternoon thunderstorms along ID/NV border Friday through Sunday. Surface winds: W-NW 7-12 kt with gusts 15 to 20 kt during the afternoons/early evenings, otherwise variable less than 10 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Air Quality Alert until 2 PM MDT Friday for IDZ011>015-028-029- 033. Heat Advisory until 9 PM MDT Saturday for IDZ012-014>016-029- 030-033. OR...Heat Advisory until 9 PM MDT /8 PM PDT/ Saturday for ORZ061>064. Air Quality Alert until 1 PM MDT /noon PDT/ Friday for ORZ061>064.