textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Breezy afternoon winds across the western Snake Plain this afternoon.

- Dry with temperatures trending 5-15 degrees above normal through early next week.

SHORT TERM /Through Friday Night/

Issued 301 AM MDT WED SEP 30 2026 Dry near-zonal flow will dominate the region today, while weak disturbances pass to the north and an upper ridge builds over the Southwest. Temperatures will warm to slightly above normal this afternoon, with fair skies expected. A weak W-NW surface pressure gradient will remain in place today and create breezy afternoon winds across the western Snake Plain. The upper ridge will continue to build into the area Thursday into early Friday, promoting calmer conditions with valley temperatures rising into the low-mid 80s. Clouds will increase on Friday while a weak disturbance passes through the area, but precipitation chances remain low.

LONG TERM /Saturday through Wednesday/

Issued 301 AM MDT WED SEP 30 2026 Southwest flow aloft will develop Saturday and Sunday as the upper ridge axis shifts west and a weak low pressure approaches the west coast. Valley temperatures will peak in the mid to upper 80s by Sunday with this enhanced southerly flow. Models indicate the weak low will briefly interrupt the ridge and move through the forecast area Monday. While NBM/WPC keep the probability of precipitation near zero, some ensemble members do indicate an increase in precipitation chances at 10-15% over the higher terrain in southwest/central Idaho due to the presence of marginal mid-level moisture. Thereafter, the ridge will rebuild and promote warm, dry, and fair conditions across southeast Oregon and southwest Idaho during mid-week.

AVIATION /18Z Wednesday through Thursday/

Issued 1148 AM MDT WED SEP 30 2026 VFR with mostly clear skies. Scattered daytime cumulus across the w-central ID mtns, bases 8-10kft MSL. Local haze due to smoke, mainly north of KBNO-KONO-KMYL. Surface winds: W to NW 5-15 kt with gusts to 20 kt through early evening then mostly light and variable overnight. Winds aloft at 10kft MSL: NW 10-20 kt.

KBOI...VFR with clear skies. Northwest surface winds through sunset with occasional gusts of 15-20 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.