726
FXUS65 KBOI 150918
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
318 AM MDT Tue Sep 15 2026

.KEY MESSAGES...
- Slight warming and drying trend Tuesday and Wednesday, with
  light winds.

- Cold temperatures tonight will bring patchy fog and frost to
  the mountain valleys.

- A low pressure system will bring light precipitation and
  isolated afternoon thunderstorms across the area Thursday and
  Friday.

&&

.SHORT TERM /Through Thursday Night/...
Overnight lows in high terrain will approach freezing, bringing
patchy valley fog and frost this morning. Southwest flow aloft
will keep daytime temperatures warm and conditions mostly dry
today and tomorrow. Winds will generally be light and terrain
driven, with mostly sunny skies. On Wednesday, a low pressure
system over western Oregon will deepen and move slightly further
east compared to previous model runs. This will bring a 40-60%
chance of precipitation over the region on Thursday, with a
slight chance of afternoon thunderstorms over northern zones.
Two day rainfall accumulations will total between 0.05-0.15
inches, with higher elevations in the West Central Mountains
approaching 0.50-0.75 inches of rain. Warm daytime temperatures
will keep snow levels above 9,000-10,000 feet MSL through the
short and long term period. Southerly winds will be elevated
over south central Idaho as the low moves into the region on
Thursday, with gusts up to 35 mph.

&&

.LONG TERM /Friday through Tuesday/...
Precipitation chances look to decrease across the region on
Friday, but mountains in central Idaho and northeast Oregon look
to keep at least a 30-40% chance of showers and a 10-15% chance
of thunderstorms through Friday night. Southerly flow aloft
will keep temperatures near normal through Friday, ahead of
cooler temperatures on Saturday with the low center moving
over the region. The low pressure system will then exit to the
east on Saturday, with showers and cooler temperatures lingering
over the central Idaho mountains. High pressure will build in
over the region on Sunday, with temperatures trending slightly
above normal (3-5 degrees) on Monday. A cold front associated
with a broad upper level trough then looks to move in sometime
on Tuesday, bringing slightly cooler temperatures and a slight
chance of mountain rain showers.

&&

.AVIATION /06Z Tuesday through Wednesday/...
Issued 1208 AM MDT TUE SEP 15 2026

Generally VFR. Areas of fog/low stratus possible overnight in mtn
valleys. Increasing high clouds this afternoon, mainly north and
west of KTWF/KJER. Surface winds: variable under 10 kt overnight
becoming E-SE 5-10 kt after Tues/17Z. Winds aloft at 10kft MSL:
W-SW 10-20 kt.

KBOI...VFR. Increasing high clouds Tue/PM. Surface winds: SE 4-10 kt
early Tue/AM. Becoming variable, leaning NW, under 10 kt Tue/PM.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.

OR...None.

&&

$$

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SHORT TERM...SA
LONG TERM....SA
AVIATION.....NF