929
FXUS65 KBOI 310007
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
607 PM MDT Thu Jul 30 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Wildfire smoke will persist across southeast Oregon and
  southwest Idaho through the weekend, keeping air quality
  degraded and hazy skies.

- A dry cold front will push through Saturday afternoon through
  Sunday, bringing gusty winds, cooler temperatures, and
  critical fire weather conditions.

&&

.SHORT TERM /Through Saturday Night/...
Issued 213 PM MDT THU JUL 30 2026
Southwest flow aloft continues across the region between a
broad upper high over the Four Corners and an approaching trough
along the Pacific Northwest coast. Very warm and dry conditions
will persist through Saturday. Wildfire smoke from several
large fires across Oregon will remain through the weekend. This
smoke will continue to degrade air quality while keeping daytime
high temperatures a few degrees lower than full solar heating
would allow. There could be some near-surface improvement in
smoke concentrations with the cold frontal passage Saturday
afternoon and evening as it promotes deeper boundary layer
mixing. Valley highs on Friday and Saturday will still reach
into the mid to upper 90s.

The main forecast focus is a dry cold frontal passage arriving
Saturday afternoon. As the front approaches, southwest to west
winds will increase Saturday morning, turning gusty from the
west-northwest Saturday afternoon and evening behind the
boundary. Wind gusts of 25 to 35 mph are expected in exposed
valley locations, high terrain, and wind-prone corridors like
the Baker Valley. Combined with afternoon relative humidity
dropping into the single digits and low teens, the gusty winds
will lead to critical fire weather conditions across much of the
area Saturday afternoon through Saturday night.

&&

.LONG TERM /Sunday through Thursday/...
Issued 213 PM MDT THU JUL 30 2026
The cold front continues east across southwest Idaho on Sunday.
Strong pressure gradients and tight thermal packing behind the
front will maintain gusty northwest winds across the area
through Sunday afternoon and evening. Gusts of 30 to 40 mph
remain possible across higher terrain and along the Snake River
Plain. Westerly winds will continue to transport wildfire smoke
across the region, keeping degraded air quality in place through
the end of the weekend. High temperatures on Sunday will drop 5
to 10 degrees behind the front, holding in the mid 80s to low
90s in the valleys.

From Monday through Thursday night, an upper-level trough over
western Canada will keep the ridge over the Great Basin and
Intermountain West largely suppressed, resulting in more
westerly flow aloft. This may prevent smoke from the Big Grass
fire from reaching the Treasure Valley, but several large fires
across eastern Oregon will continue to spread smoke across
western Idaho. Thus, smoky conditions are likely to persist
through the end of the week. A steady drying trend will
continue, with lower elevation temperatures returning to the mid
90s by Wednesday and Thursday. Winds will subside compared to
the weekend, returning to typical afternoon breezy conditions.
With limited moisture return, precipitation chances remain near
zero across southeast Oregon and southwest Idaho through
Thursday night.

&&

.AVIATION /00Z Friday through Saturday/...
Issued 557 PM MDT THU JUL 30 2026
Widespread wildfire smoke reducing visibilities with areas of
MVFR and IFR conditions. Surface winds: SW-NW 5-12 kt through
this evening. Gusty valley winds 10-15 kt with gusts 20-25 kt
over KBKE and KONO in the evening, subsiding after midnight.
Winds aloft at 10kft MSL: SW 5-15kt.

KBOI...Smoke reducing visibility. Surface winds: NW 5-10 kt,
shifting to SE 5-10kt after sunset.

Weekend Outlook...Smoke reducing visibility. Dry frontal
passage on Saturday will bring gusty NW winds over all areas
Saturday afternoon/evening and mainly east of KBOI Sunday
afternoon. This could improve the dense smoke coverage for some
areas. Surface winds: SW-NW 10-20 kt with gusts 20-30 kt
Saturday/Sunday.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Air Quality Alert until 2 PM MDT Friday for IDZ011>015-028-029-
     033.
     Fire Weather Watch from Saturday afternoon through Saturday
     evening for IDZ402-423.
OR...Fire Weather Watch from Saturday afternoon through Saturday
     evening for ORZ670>675.
     Air Quality Alert until 1 PM MDT /noon PDT/ Friday for
     ORZ062>064.
&&

$$

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AVIATION.....KA
SHORT TERM...JDS
LONG TERM....JDS