textproduct: Boise

KEY MESSAGES

- Hot with widespread wildfire smoke persisting across southeast Oregon and much of southwest Idaho through Saturday.

- Dry cold front Saturday evening will bring period of critical fire weather conditions and gusty winds.

- Remaining dry but not as hot Sunday through Tuesday. The heat returns by midweek.

SHORT TERM /Through Sunday Night/

An upper high over the Desert SW will keep the heat on through Saturday. Temperatures will again touch 100 degrees at lower elevations with locally hotter temperatures (Mountain Home to Hagerman) pushing above 100 degrees on Saturday. Flow aloft will increase on Saturday as an upper trough pushes into the Pac NW. Higher, open terrain in SE Oregon and SW Idaho will tap into the southwest winds, bringing gusts to 30 mph by afternoon. The upper trough and accompanying cold front advance inland Saturday evening pushing a dry cold front into SE Oregon by late afternoon, advancing into SW Idaho during the evening. Winds gusts will be strongest across SE Oregon, especially along the I-84 corridor between Baker City and Ontario where gusts to 45 mph are expected into Saturday night. For Baker County have opted to cover the wind threat with an Advisory picking up where the Red Flag Warning leaves off as relative humidity will be on in the increase, but but gusty winds will continue into Saturday night. Elsewhere wind gusts top out between 25 and 40 mph across SE Oregon and the Snake Plain/Highlands of SW Idaho through Saturday night.

For Sunday the post frontal air mass is dry with high temperatures 10-15 degrees cooler than Saturday. It will remain breezy as westerly winds reside through the mixed layer. This will result in elevated, but not quite critical fire weather conditions as afternoon relative humidity drops to around 10% across lower elevations. Forecast models are cutting down on smoke coverage for Sunday as westerly flow in a well mixed environment vents out the smoke that has pooled up over the last week(ish) and modeled plumes from ongoing fires are tighter. Do expect some improvement going into early next week, but uncertain on how much, especially if there are new starts or Saturday's wind/RH event kicks up current activity. Sunday night will be cool compared to the recent past with temperatures dropping below 60 across the Snake Plain. Officially for Boise this would be the first sub-60 degree temperature since July 3rd.

LONG TERM /Monday through Friday/

After the aforementioned cool start, lower elevations will see another dry, sub-90 degree day on Monday. Winds will pick up across SE Oregon and the Snake Plain of Idaho as westerly flow aloft mixes to the surface. The upper trough providing the cooler, breezy conditions will slide east of the area Tuesday, allowing for warm temperatures to return. By Wednesday highs are back into the mid-upper 90s across lower elevations (smoke coverage/density dependent). There is no chance for precipitation next week as monsoon moisture remains bottled up over the Four Corners. The hot and dry conditions will be favorable for fire growth so smoke is likely to increase in coverage and density.

AVIATION /18Z Friday through Saturday/

Issued 1219 PM MDT FRI JUL 31 2026 Wildfire smoke will continue to reduce visibility across the region through Saturday. Mostly MVFR to lower VFR conditions, with local IFR across SE Oregon and along the OR/ID border. Hot conditions will produce high density altitude through Saturday afternoon. Surface winds: variable under 12 kts. Winds aloft at 10kft MSL: S 5-15 kt.

KBOI...Low VFR visibility in smoke. Light surface winds through tonight.

Weekend Outlook...Wildfire smoke will keep widespread visibility reduction in place through Saturday, mostly across SE Oregon. Coverage is expected to decrease and visibility will improve on Sunday. High density altitude due to hot conditions on Saturday. Gusty SW-NW surface winds 25 to 40 kt Saturday night decreasing to 15-20 kt Sunday.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Air Quality Alert until 2 PM MDT Monday for IDZ011-012-014-015- 029-033. Red Flag Warning from 3 PM to 9 PM MDT Saturday for IDZ400-402- 423. OR...Red Flag Warning from 3 PM MDT /2 PM PDT/ to 9 PM MDT /8 PM PDT/ Saturday for ORZ670>675. Air Quality Alert until 3 PM MDT /2 PM PDT/ Monday for ORZ061>064. Wind Advisory from 8 PM Saturday to 2 AM PDT Sunday for ORZ062.