textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Continued hot Sunday then gradual cooling through the coming week.

- Smoke persisting into the coming week.

- Breezy afternoon winds through Monday.

- Isolated late-day thunderstorms with gusty outflow winds and little rain near the ID/NV border through Monday.

SHORT TERM /Through Monday Night/

Issued 133 PM MDT SAT AUG 8 2026 Widespread smoke continues over our CWA, with a large part coming from wildfires in south-central OR. Smoke is thick enough to inhibit daytime heating but we will let our Heat Advisory continue until 9 PM MDT expiration time. Note that smoke cuts down on daytime heating but does not interfere with nighttime cooling. The forecast has gradual daytime cooling anyway as the Great Basin upper ridge weakens and shifts south and east, so we don't expect to issue any more Heat Advisories and our hottest summer weather may already be behind us.

Meanwhile, mid and high-level monsoon moisture has reached our southern CWA border and a few weak radar echoes have appeared in southern Owyhee County as of 1 PM MDT. These should increase through the afternoon with a slight boost from a weak cold front approaching from the north Pacific, leading to isolated high-based thunderstorms in Owyhee and Twin Falls County through sunset. The lower atmospheric levels will stay dry, however, and little if any rain will reach the ground, but storms may still produce strong downdrafts and outflow winds. The same can be expected Sunday and Monday afternoons/evenings, with southern Twin Falls County the target area on those days.

Latest smoke model forecasts suggest some improvement by Monday but with fires ongoing in Oregon we have our doubts. Current air quality advisories from both Idaho and Oregon Department of Environmental Quality (DEQ) remain in effect through midday Monday.

LONG TERM /Tuesday through Saturday/

Issued 133 PM MDT SAT AUG 8 2026 Gradual day-to-day cooling should continue through Saturday with temps finally lowering to normal or even slightly below normal. Zonal flow aloft should push the monsoon moisture back south of our CWA on Tuesday, but a Pacific trough along the BC coast will turn upper winds to southwesterly again Wednesday and beyond, with monsoon moisture again getting into our southern zones, with gradually increasing chances of showers and thunderstorms. Northern CWA zones should stay dry, however.

AVIATION /00Z Sunday through Monday/

Issued 534 PM MDT SAT AUG 8 2026 Widespread MVFR visibility and mountain obscuration due to wildfire smoke. High density altitude due to hot afternoon temperatures. Thunder is unlikely in convection along the ID/NV border. Surface winds: W-NW 10-20 kt this afternoon, with gusts 20-25 kt near KBKE and KONO, becoming light and variable tonight. Winds aloft at 10kft MSL: W-SW 10-20 kt.

KBOI...MVFR visibility possible due to wildfire smoke. Periods of foothill obscuration. Surface winds: NW 5-10 kt with gusts up to 18 kt this afternoon through evening, shifting SW 5-10 kt late tonight through Sunday morning.

BOI WATCHES/WARNINGS/ADVISORIES

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