textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Continued very warm, dry days through Friday.

- Much cooler, with showers, Saturday through Tuesday.

- Significant rainfall possible in Idaho Monday and Tuesday.

SHORT TERM /Through Thursday Night/

Issued 210 PM MDT TUE OCT 6 2026 Upper level high pressure will continue warm, dry days through Thursday. Mostly clear skies and light winds will allow good radiational cooling at night and low temps in the 40s to lower 50s, except 30s in colder mountain valleys. Winds will continue light and terrain-driven.

LONG TERM /Friday through Tuesday/

Issued 210 PM MDT TUE OCT 6 2026 One final day of warm and dry conditions is expected Friday before a major pattern change Saturday through Tuesday. An upper-level trough will move south from British Columbia, increasing wind speeds in higher terrain as it moves closer to the area. A cold front will move across the area on Saturday, cooling high temperatures by about 20 degrees areawide from Friday. Breezy winds will expand to lower elevations as the front moves through.

The trough is favored to close off and dive south through the Pacific Northwest, moving into SE Oregon and SW Idaho Saturday into Sunday. Once late Sunday into Monday rolls around, models are split on having the system move even further south into CA/NV or staying progressive and moving east. These range of solutions greatly increase uncertainty early next week, as ensembles have consistently developed significant precipitation to the east of the low center where better moisture will exist. The current forecast is a 40-60% chance of precipitation across central Idaho Saturday night through Tuesday, with a 10-30% chance elsewhere. Temperatures are expected to decrease to 5 to 10 degrees below normal Sunday through Tuesday, which will also take many higher elevations to below freezing during overnight periods. Temperatures low enough for frost at lower elevations may also occur, but confidence in that is low currently. Cooler air will also mean lower snow levels, allowing for snow on the higher peaks. However, similar to the precipitation forecast, how much cooler depends on the exact track of the low. The most aggressive model guidance has snow levels in SE Oregon getting near 4000 feet at the lowest. Winds will remain breezy through Sunday, then start to subside early next week.

AVIATION /06Z Wednesday through Thursday/

Issued 1150 PM MDT TUE OCT 6 2026 VFR. Clear skies. Areas of smoke and haze may reduce visibility near prescribed burns. Surface winds: variable less than 12 kt. Winds aloft at 10kft MSL: W 5-15 kt.

KBOI...VFR with clear skies. Surface winds: SE less than 5 kt tonight becoming NW 5-10 kt Wednesday afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.