084
FXUS65 KBOI 172321
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
521 PM MDT Mon Aug 17 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Isolated showers and thunderstorms this afternoon over higher
  terrain, with gusty outflows up to 35 mph.

- Temperatures near or slightly above normal through mid-week,
  then heat amplifying for Thursday and Friday.

- Return of monsoon moisture Friday into the weekend will
  increase shower and thunderstorm chances once again.

&&

.SHORT TERM /Through Wednesday Night/...
Issued 205 PM MDT MON AUG 17 2026
A distinct line of very light showers is currently pushing north
over the Treasure Valley and Malheur County, with minimal
precipitation amounts observed as of 2pm MDT. Cloud cover will
continue to persist through the evening, with a weak shortwave
trough moving through the region this afternoon. This will
continue the 10-20% chance of showers and thunderstorms,
primarily over the central ID mountains and near the high
terrain over the NV-ID border. The primary hazards with any of
these thunderstorms will be gusty outflows up to 35 mph and
lightning. Thunderstorm potential is slightly lower than
previously forecast due to the widespread persistent cloud
clover this afternoon. Lingering moisture over eastern Valley
County tomorrow will keep a 5-10% chance of showers and
thunderstorms through the evening. High pressure will build
back in over the Intermountain West tomorrow through the end of
the short term period, bringing a steady warming and drying
trend with generally light winds. Smoke from Oregon/Washington
wildfires will filter into the region tomorrow, with the
thickest smoke over Baker County, OR.

&&

.LONG TERM /Thursday through Monday/...
Issued 205 PM MDT MON AUG 17 2026
The Four Corners upper-level ridge will continue to build Thursday
and Friday with the Pacific low pressure system slowly moving
towards the shore. Southwesterly flow aloft will transition to
increased southerly winds through much of the weekend. This pattern
will bring back summertime heat risk, with temperatures climbing to
near 100 degrees for lower elevations. Precipitation chances will
start isolated in the higher terrain of SW Idaho Thursday,
increasing to most higher elevations across SW Idaho and SE Oregon
Friday. Afternoon wind gusts will also become breezier late week
into the weekend. The upper-level trough will move onshore late
Friday into Saturday and quickly move NE through the Pacific NW and
Northern Rockies. Cooling temperatures to near-normal are forecast
Saturday and Sunday with this disturbance moving through.

&&

.AVIATION /00Z Tuesday through Wednesday/...
Issued 517 PM MDT MON AUG 17 2026
VFR. Weak, isolated showers/thunderstorms continuing through this
evening over west-central ID mtns and near KTWF/KJER. Erratic
outflows to around 35 kt possible in storms. Patchy surface
smoke near KBKE/KBNO tonight through Tuesday morning. Surface
winds: variable or NW 5-10 kt this evening, becoming mostly
light and variable overnight. Winds aloft at 10kft MSL:
W 5-15 kt.

KBOI...VFR. Possible storm outflows to 30 kt this evening
through sunset. Surface winds: NW-N 5-10 kt, then variable under
7 kt tonight after sunset.

&&

.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.....JY
SHORT TERM...SA
LONG TERM....CH