105
FXUS65 KBOI 301800
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1200 PM MDT Wed Sep 30 2026

.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.

&&

$$

www.weather.gov/Boise

Interact with us via social media:
www.facebook.com/NWSBoise
www.x.com/NWSBoise

AVIATION.....DG
SHORT TERM...SH
LONG TERM....SH