FXUS65 KBOI 202021

AFDBOI



Area Forecast Discussion

National Weather Service Boise ID

221 PM MDT Sun Sep 20 2026



.KEY MESSAGES...

- Mostly dry with warming temperatures through Thursday.



- Chance of showers and thunderstorms Tuesday, mostly across

  higher terrain of southwest Idaho.



- Cooler temperatures heading into next weekend with a chance of

  precipitation across SE Oregon and portions of SW Idaho

  Friday.

 

&&



.SHORT TERM /Through Tuesday Night/...

Broad upper ridging will keep warm and dry conditions over the

region on Monday. Temperatures will warm several degrees from

today's highs, reaching 5-10 degrees above normal. An eastward 

shift in the ridge axis on Tuesday will allow for a closed low 

to lift northeastward through the Great Basin. This will bring a

20-30% chance of showers and thunderstorms to higher terrain 

along the northern NV border, the w-central Idaho mtns east of 

McCall- Lowman- Prairie and the mtns in Baker County Tuesday 

afternoon. Potential inhibiting factors for development would 

be daytime cloud cover and eastern track of the low/dynamic 

center. Temperatures are mostly unchanged on Tuesday with a few 

degrees of cooling anticipated across w-central Idaho zones.



&&



.LONG TERM /Wednesday through Sunday/...

A ridge will remain over the area through Friday with above 

normal temperatures. A trough moves into the Pacific NW sometime 

on Friday or Saturday with cooler temperatures and increased 

chances (15 to 25 percent) of precipitation next weekend. 

Precipitation chances will be highest north of Burns OR to 

McCall ID, with generally dry conditions near the NV border. 

Temperatures around 10 degrees above normal Wednesday and 

Thursday, before falling to near normal on Friday, and 5 to 10 

degrees below normal on Saturday and Sunday.



&&



.AVIATION /18Z Sunday through Monday/...

Issued 1232 PM MDT SUN SEP 20 2026

VFR. Patchy mountain valley fog overnight. Surface winds: 

variable 5-10kt. Winds aloft at 10kft MSL: variable 5-15kt.



KBOI...VFR. Surface winds: NW 5-10kt becoming SE 5-10kt after  

sunset.



&&



.BOI WATCHES/WARNINGS/ADVISORIES...

ID...None.



OR...None.



&&



$$



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SHORT TERM...DG

LONG TERM....KA

AVIATION.....KA