textproduct: Boise

KEY MESSAGES

- Warm and dry conditions will persist over the next several days.

- Smoky conditions will limit high temperatures by a few degrees and continue degraded air quality into the weekend.

SHORT TERM /Through Wednesday Night/

Southwesterly flow aloft will remain firmly in place across the forecast area through Wednesday night. This pattern is anchored by high pressure over the Desert Southwest and low pressure off the Pacific Northwest coast. The southwesterly flow will continue to transport wildfire smoke from several large fires across southeast Oregon into southwest Idaho, resulting in persistent haze, degraded air quality, and reduced surface visibilities.

Smoke cover will continue to moderate afternoon high temperatures across lower valleys, keeping daytime highs near or slightly below seasonal normals for late July. General conditions will remain dry with light to moderate afternoon surface breezes. Nocturnal and early morning surface inversions, along with downvalley drainage winds, will keep smoke localized in valley floors, particularly in the Treasure Valley and Baker Valley corridors, before mild afternoon mixing offers brief, temporary visibility improvements.

LONG TERM /Thursday through Monday/

With troughing over British Columbia and high pressure aloft over the Four Corners, hot, dry, and breezy conditions will continue to end the week. This pattern doesn't appear promising in reducing impacts from wildfire smoke. Smoke acting to block incoming solar radiation could be a failure mode in terms of the temperature forecast. The general pattern would favor temperatures climbing to around 5 degrees above normal Thursday through Saturday, as the high pressure aloft shifts to be over the Great Basin... but smoke impacts may moderate temperatures to be near normal. Come Sunday, the aforementioned British Columbia trough and it's associated cold front will cross over our area. This will be a dry cold frontal passage, bringing gusty winds, and near or even slightly below normal temperatures come Sunday and Monday.

AVIATION /18Z Monday through Tuesday/

Issued 1043 AM MDT MON JUL 27 2026

Wildfire smoke resulting in areas of MVFR/IFR horizontal visibility, and significantly reduced slantwise visibility. Mtns obscured in smoke. Slight improvement in the afternoon before degrading again overnight and early Tue/AM. Surface winds: SW-NW 5-15 kt. Gusts to 20-25 kt in portions of E-Oregon and higher terrain of SW-Idaho this afternoon/evening. Winds aloft at 10kft MSL: SW 5-15 kt.

KBOI...Wildfire smoke resulting in MVFR/IFR visibilities. Some improvement this afternoon, before degrading again overnight and early Tue/AM. Surface winds: NW 8-12 kt with gusts to around 18 kt this afternoon. Then light and variable overnight.

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 Wednesday for IDZ016-030. OR...Air Quality Alert until 1 PM MDT /noon PDT/ Wednesday for ORZ061>064.