textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Cool and dry today then warmer Mon and Tue.

- Chance of thunderstorms in S-central ID Mon, and Central ID Tue afternoons.

- A strong low pressure system expected later this week will bring cooler, windier, and wetter conditions.

SHORT TERM /Through Tuesday Night/

Issued 203 PM MDT SUN AUG 30 2026 Cooler temps today and clear skies will be short lived as a brief ridge builds in Monday alongside warmer southwesterly flow. Temperatures warm about 10 degrees Sunday into Monday, right around seasonal averages for this time of year. Behind the shortwave ridge, a strong upper level low pressure system brings a significant shift Tuesday onwards. The moisture ahead of this system will support isolated thunderstorms in the Magic Valley Monday. Thunderstorm activity moves north into the Central Idaho highlands and mountains for Tuesday. Additionally, winds begin to increase Tuesday afternoon, with gusts up to 30 mph across the area outside of sheltered valleys. The warmer temps are shortlived Monday and Tuesday, before a cool down Tuesday night as the low moves properly into the region.

LONG TERM /Wednesday through Sunday/

Issued 203 PM MDT SUN AUG 30 2026 A chance of precipitation will follow the exiting shortwave trough on Wednesday as a deeper closed low drops down the coast. Initially the low is fairly broad as it spans the exiting trough. This will keep a 30-60% chance of showers across SE Oregon and the w-central ID mtns through Thursday. Precipitation retracts westward on Friday as the low consolidates along the Oregon coast and the region falls under a drier southerly flow, out of the reach of the deeper moisture and dynamics. From here we'll be watching for when/how the low lifts eastward as this could bring another round of showers and possible thunderstorms. Early guidance would indicate late in the weekend or early next week. The S/SW flow aloft will favor gusty afternoon winds over elevated terrain, the stronger gusts across Harney, Malheur and Owyhee counties. Late afternoon/evening wind pushes across SE Oregon could shift winds to the NW for Thur/Fri. The temperature spread (10-90%tile) increases to 20 degrees for Thur- Sun with the ensemble mean placing high temperatures near or slightly below normal.

AVIATION /00Z Monday through Tuesday/

Issued 356 PM MDT SUN AUG 30 2026

VFR under clear skies. Localized visibility reductions due to smoke near wildfires in Baker County and Boise Mountains. Surface winds: W-NW 5-15 kt this evening, then light and variable overnight. Winds aloft at 10kft MSL: W 5-15 kt.

KBOI...VFR under clear skies. NW under 10 kt winds becoming SE under 10 kt winds overnight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.