textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Isolated afternoon thunderstorms Tuesday and Wednesday, mainly forming over the Idaho mountains, and southern Twin Falls County on Thursday afternoon.

- Heavy rains possible on Friday afternoon from scattered thunderstorms over southwest Idaho. Some of the storms may be severe.

- A slight warming trend Tuesday and Wednesday, then gradually cooling the rest of the week with breezy conditions.

SHORT TERM /Through Thursday Night/

Issued 408 AM MDT TUE AUG 25 2026 An upper level ridge axis will remain just east of the area Tuesday and Wednesday while low pressure remains situated off the Pacific Northwest. This will keep southwest flow over the area with temperatures trending up slightly. Breezy southwest winds expected on Tuesday, Wednesday and Thursday afternoon over eastern OR and the southwest ID highlands. Enough moisture remains over southwest Idaho for isolated afternoon thunderstorms Tuesday and Wednesday, mainly forming over the mountains, and southern Twin Falls County on Thursday afternoon. Gusty outflow winds up to 50 mph will be the main threat with thunderstorms, especially over Twin Falls County over the next several afternoons.

LONG TERM /Friday through Tuesday/

Issued 408 AM MDT TUE AUG 25 2026 A ridge will remain over the Four Corners region through Saturday. Tropical Storm Iselle is forecast to weaken and portions of the remnants will get ingested into the southwest flow aloft off the CA coast and move over southwest Idaho and extreme SE Oregon on Friday afternoon. Magic Valley precipitable waters reach the 98th percentile with this feature so heavy rain will be a threat with storms that form across the southwest ID highlands, central ID mountains and southern Twin Falls County. A cold front will interact with this moisture and enhance thunderstorm development on Friday afternoon. This moisture will be quick to move through however and clears the area by early Saturday morning with dry and cooler conditions thereafter. Temperatures will be near normal Friday and Saturday before cooling to below normal Sunday and Monday as a trough passes by to the north. Temperatures rebound to near normal Tuesday with west-southwest flow.

AVIATION /12Z Tuesday through Wednesday/

Issued 616 AM MDT TUE AUG 25 2026 VFR. Areas of wildfire smoke. Isolated thunderstorms this afternoon and evening, mainly south of KBOI, east of KMYL and near KTWF KJER, capable of producing erratic wind gusts up to 45kt. Surface winds SW-SE 5-15kt.

KBOI...VFR. SE 5-10kt this morning, shifting to NW 5-10kt during the afternoon, and SE 10-15kt this evening.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...Air Quality Alert until noon PDT Wednesday for ORZ062.