624
FXUS65 KBOI 261756
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1156 AM MDT Sat Sep 26 2026

.UPDATE...Updated aviation discussion.

&&

.KEY MESSAGES...
- Temperatures will remain cool today, ranging 5-10 degrees
  below normal.

- A slight chance of showers and afternoon thunderstorms in
  portions of southeast Oregon and central Idaho on Sunday.

- Seasonable temperatures and dry conditions expected Monday
  through late week.

&&

.SHORT TERM /Through Monday Night/...
Issued 245 AM MDT SAT SEP 26 2026
Winds have become light this morning following the cold front`s
departure to the east. Current satellite imagery depicts areas
of low stratus and patchy mountain valley fog across northeast
Oregon and north-central Idaho this morning, attempting to
expand south into Baker County and west-central Idaho. However,
dense high clouds arriving from the west will be a limiting
factor for fog coverage.

In the wake of the cold front, a cool airmass will settle
over the forecast area today. Afternoon temperatures will run
5-10 degrees below normal, and roughly 20-25 degrees cooler
than Thursday`s high temperatures. Conditions will remain dry
today, though mid-level moisture and virga will increase ahead
of a weak trough approaching the West Coast. With moisture
continuing to stream in tonight and Sunday, precipitation
chances will gradually increase Sunday morning through Sunday
evening. Rainfall amounts should be relatively light, with the
highest chances (20-30%) focused over southeast Oregon and
central Idaho. While the cloud cover will limit daytime
instability, a couple of afternoon lightning strikes will remain
possible during peak heating hours. Meanwhile, the southwest
flow aloft will nudge temperatures back up on Sunday, warming
within a couple degrees of normal. The trough is then projected
to cut off and track through California/Nevada by Monday,
introducing a drier west-northwest flow aloft across the
forecast area.

&&

.LONG TERM /Tuesday through Saturday/...
Issued 245 AM MDT SAT SEP 26 2026
A fair weather pattern will dominate Tuesday through late week
under dry westerly flow aloft. This pattern will support near-
seasonable temperatures throughout the extended period. Model
guidance begins to diverge Friday and Saturday, with some
members favoring cooler temperatures tied to upper-level
troughing while others lean toward building high pressure.
Regardless of temperature variations, mostly dry conditions
should prevail into the weekend.

&&

.AVIATION /18Z Saturday through Sunday/...
Issued 1141 AM MDT SAT SEP 26 2026
VFR with BKN-OVC high cloud coverage this evening through early
Sunday. Surface winds: NE-NW 5-12 kt this afternoon. Winds
aloft at 10kft MSL:
SW 10-25 kt.

KBOI...VFR with BKN high clouds. Surface winds: W-NW up to 10
kt.

Sunday Outlook...VFR with dense mid-high level cloud coverage.
Isolated rain showers, mainly over SE Oregon and central ID
mountains in the morning through evening. Up to a 10% chance of
afternoon lightning strikes over high terrain areas. Surface
winds: variable up to 10 kt in the morning, becoming SW-NW 5-15
kt with gusts to 15-20 kt in the afternoon.

&&

.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...SH
LONG TERM....SH