textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Temperatures continuing 5 to 10 degrees above normal through Thursday.

- Slight chance of thunderstorms over higher terrain Wednesday and Thursday afternoons with gusty outflow winds but little, if any, rain.

- Major weather change beginning Friday with arrival of a north Pacific cold front. Showers, thunderstorms, gusty winds, and much cooler air lasting through Monday. Snow possible as low as 6500 feet MSL Saturday night and Sunday.

SHORT TERM /Through Friday Night/

Issued 218 PM MDT TUE JUN 23 2026 A weak upper ridge will maintain hot weather through Thursday with enough instability for isolated high-based afternoon and evening thunderstorms. Storms will produce gusty outflow winds but little, if any, rain. A strong north Pacific cold front will pass through eastern Oregon pre-dawn Friday, beginning a change to wetter and much cooler weather.

LONG TERM /Saturday through Wednesday/

Issued 218 PM MDT TUE JUN 23 2026 A closed upper low will steer into the northwest region from off the coast of British Columbia on Friday. This pattern will bring a cold front through southwest ID on Friday with cooler and unsettled conditions through Saturday and Sunday. Widespread showers and thunderstorms are expected throughout Friday with this frontal passage, with the highest chances in the afternoon. There is slightly better guidance agreement over the upper low center moving right over our area on Saturday. As such, Saturday and Sunday will see the highest chances of wetting rain, mainly over the west-central ID mountains, with temperatures as much as 20-30 degrees below normal area-wide. With snow levels expected to drop down into the 6000-7000 ft MSL range by early Sunday, light snowfall remains possible on mountain peaks late Saturday through Sunday morning. Conditions dry out with breezy conditions on Monday and Tuesday as the system moves northeast into west-central Canada. Our area will likely stay under a drier shortwave trough behind the system and remain in a cooler pattern from a northwest flow early next week.

AVIATION /06Z Wednesday through Thursday/

Issued 1225 AM MDT WED JUN 24 2026 VFR. High Density Altitude Wed/PM due to hot temperatures. Isolated showers/thunderstorms developing Wed/PM, mainly near the ID/NV border. Thunder capable of erratic outflows to 35 kt. Surface winds: Variable 5-10 kt overnight. Then W-NW 10-15 kt with gusts to around 20 kt Wed/PM. Winds aloft at 10kft MSL: Variable 5-15 kt.

KBOI...VFR. High Density Altitude Wed/PM due to hot temperatures. Surface winds: Variable (leaning S-SW) 3-6 kt overnight, then NW 8- 12 kt with gusts to around 20 kt Wed/PM.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.