textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Hot and dry through the weekend.

- Isolated storms in the Magic Valley and ID southern highlands this afternoon.

- Smoke will limit high temperatures and continue degraded air quality through the end of the week.

- A dry cold front this weekend will bring critical fire weather with gusty winds and very dry conditions.

SHORT TERM /Through Friday Night/

Issued 338 AM MDT WED JUL 29 2026 The large high pressure system sitting over the Four Corners region will slowly shift into the Great Basin, continuing weak to moderate southwest flow and dry conditions through the rest of the week. Elevated temperatures around 5 degrees above normal are expected Thursday through Friday. The weak southwest flow will continue the intrusion and persistence of dense wildfire smoke over the area with little improvements expected, degrading air quality through the remainder of the week. Smoke over the area may continue to limit daytime mixing and slightly moderate peak afternoon temperatures by a few degrees. A Pacific shortwave trough will steer across the Great Basin and our area today, bringing isolated thunderstorms over the Magic Valley and portions of the southern Owyhee highlands in the afternoon. Isolated storms will be capable of producing gusty outflows 40 to 50 mph. A smaller and weaker shortwave will pass by the eastern OR side on Thursday, bringing a low probability (around 5%) of afternoon thunderstorms over east-central OR. The area will remain hot, dry, and slightly breezy on Friday.

LONG TERM /Saturday through Wednesday/

Issued 338 AM MDT WED JUL 29 2026 Saturday is forecasted to see the hottest temperatures of the week, but dense smoke may persist and continue to slightly moderate peak temperatures. A stalled upper low over British Columbia will begin to move inland through Saturday and is set to bring a dry cold front through the area Saturday evening into Sunday. With Saturday being the hottest day, this combination of heat, very dry conditions, and frontal gusty winds will lead to critical fire weather conditions across the area. Behind the cold front, Sunday through Monday will be 5-10 degrees cooler than normal, but dry and gusty conditions will remain, leading to continued elevated fire weather conditions. Temperatures begin to climb again Tuesday and Wednesday as a Pacific high pressure system builds into the West Coast and Desert Southwest. Warm and dry conditions will remain through midweek in the extended period.

AVIATION /12Z Wednesday through Thursday/

Issued 503 AM MDT WED JUL 29 2026 Widespread wildfire smoke reducing visibilities with MVFR to IFR conditions. Mountains obscured in smoke. Isolated thunderstorms SE of KTWF and KJER this afternoon with gusty winds up to 45kt in vicinity of storms. Surface winds: mostly variable under 10 kt this morning, except valley winds NW 10-15 kt with gusts to 25 kt near KONO, becoming SW-NW 5-10 kt in the afternoon. Winds aloft at 10kft MSL: SW 5-15kt.

KBOI...MVFR conditions from wildfire smoke through early afternoon. Possible improvements in the later afternoon. Surface winds SE 4-7kt this morning, becoming NW 5-10 kt with gusts up to 17 kt in the afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Air Quality Alert until 2 PM MDT Friday for IDZ011>015-028-029- 033. Air Quality Alert until 1 PM MDT this afternoon for IDZ016-030. OR...Air Quality Alert until 1 PM MDT /noon PDT/ this afternoon for ORZ061>064.