903
FXUS65 KBOI 142005
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
205 PM MDT Mon Sep 14 2026

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

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

- Another low pressure system will bring precipitation across
  the area Thursday and Friday.

&&

.SHORT TERM /Through Wednesday Night/...
Breezy and cool conditions will gradually diminish this evening
as the upper low moves further northeast away from the area.
Warm and dry conditions expected tonight under generally clear
skies. Excellent radiational cooling will allow minimum
temperatures to drop to around 5 degrees below seasonal
averages. Patchy frost is possible in the sheltered mountain
valleys by early Tuesday morning.

A weak ridge aloft will build over the region Tuesday into
Wednesday, leading to a slight warming and drying trend with
lighter winds. This is in response to a developing cut-off low
pressure system forming over Western Oregon. Afternoon high
temperatures will rebound closer to normal values for mid
September. By late Wednesday, the low pressure system begins to
slowly move inland. Southwest flow ahead of this system will
bring increasing cloud cover and an influx of mid level moisture
to eastern Oregon and southwestern Idaho, with low chances for
precipitation entering western areas late Wednesday night.

&&

.LONG TERM /Thursday through Monday/...
The end of the work week will remain unsettled, with an upper-
level low pressure system moving overhead. Precipitation chances
will be highest in the west-central Idaho mountains (50-70%
chance), with mentionable chances elsewhere (15-40% chance),
lowest in the valleys. After this system moves out, an upper-
level ridge will build into the NW U.S., bringing a clearing and
warming trend back to the area. Models are split on the forecast
starting next week, but a return to another unsettled pattern
looks to return.

&&

.AVIATION /18Z Monday through Tuesday/...
Issued 1217 PM MDT MON SEP 14 2026

VFR. Scattered low stratus across Baker County and the west-
central Idaho mountains creating mountain obscuration, mixing
out by early afternoon. Surface winds: SW-NW 5-15 kt. Winds
aloft at 10kft MSL: W to NW 5-20 kt.

KBOI...VFR. Mid-level clouds over the foothills clearing through
the afternoon. Surface winds: NW near 10 kt becoming variable
less than 5 kt this evening, then E-SE 4-8kt by Tues/10Z.

&&

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

OR...None.

&&

$$

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SHORT TERM...JDS
LONG TERM....CH
AVIATION.....CH