113
FXUS65 KBOI 092000
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
200 PM MDT Sun Aug 9 2026

.KEY MESSAGES...

&&

.SHORT TERM /Through Tuesday Night/...

- Continued hot, dry, and smoky into Tuesday.

- Breezy afternoon winds through Tuesday.

- Gradual cooling through the week.

- Increasing chance of showers and thunderstorms Wednesday
  and beyond, especially on the Idaho side.

&&

.SHORT TERM /Through Tuesday night/...
Hot, dry, smoky weather will continue through Tuesday,
although not as hot as previous days as high pressure aloft
gradually weakens over the Great Basin. Southern Twin Falls
County will remain on the northern fringe of monsoon moisture
with isolated thunderstorms late today and again late Monday.
Westerly winds aloft will change to southwesterly Tuesday as
an upper trough deepens off the northwest coast. This change
will allow monsoon moisture to move northward across the NV/ID
border for a 15-20% chance of showers and thunderstorms late
Tuesday, continuing in Twin Falls County Tuesday night. Smoke
continues to stream across our CWA mainly from the Big Grass
fire (in southern Malheur County and western Owyhee County),
and from the Wright Springs fire in south-central Oregon.
Latest RRFS model forecasts less smoke in our CWA by Tuesday
but confidence is low.

.LONG TERM /Wednesday through Sunday/...
High pressure will build over the Desert Southwest as a weak
trough moves into the West Coast on Wednesday. This will bring
southwest flow over the region, which will cool temperatures
slightly, as the high pressure center shifts further east.
Monsoonal moisture will advect northward, but long range models
keep the best chances of associated showers and thunderstorms
to our south and east through Thursday. By Friday, models
substantially increase precipitation coverage over high terrain
through the weekend. The Central Idaho Mountains and high
terrain along the Nevada border will see the best chance for
showers and thunderstorms (20-40% chance). Warm and breezy
conditions will continue through the weekend, with temperatures
slightly below normal through the weekend. High temperatures in
the valleys will range from the mid to upper 80s through
Saturday, with high temperatures in the mountains in the mid to
upper 70s.

&&

.AVIATION /18Z Sunday through Monday/...
Issued 1146 AM MDT SUN AUG 9 2026

Generally VFR with periods of MVFR conditions near KONO-KEUL
in thicker smoke from nearby wildfires. Mountains obscured in
smoke. High density altitude with hot afternoon temperatures.
Surface winds: W-NW 5-10 kt, variable less than 10 kt overnight.
Winds aloft at 10kft: W-SW 10-20 kt.

KBOI...MVFR conditions in smoke improving to VFR conditions by
mid-afternoon. Foothills obscured in thicker smoke. High density
altitude with hot afternoon temperatures. Surface winds: NW 6-8
kt, variable less than 6 kt overnight.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Air Quality Alert until 1 PM MDT Monday for IDZ011>015-028-029-
     033.
OR...Air Quality Alert until 1 PM MDT /noon PDT/ Monday for
     ORZ061>064.
&&

$$

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SHORT TERM...LC
LONG TERM....LC
AVIATION.....SA