FXUS65 KBOI 122046

AFDBOI



Area Forecast Discussion

National Weather Service Boise ID

146 PM MST Fri Dec 12 2025



.SHORT TERM...Tonight through Sunday night...An large upper 

level ridge will remain over the area. Expect mostly clear 

skies with light winds. Afternoon temperatures will be 15 to 20

degrees above normal for this time of year. The light winds, 

low mixing heights, and a strong night time temperature 

inversion will also trap air pollution in valley locations. An 

air stagnation advisory has been issued for these conditions 

which will continue through the weekend. There isn't enough 

moisture to produce widespread foggy conditions that are 

typical during an inversion, but patchy morning fog is still 

possible in lower valley locations.



LONG TERM...Monday through Friday...A longwave Pacific trough is 

expected to steer into the region Monday, ramping up precipitation 

chances across the forecast area late Monday as the first wave of 

Pacific moisture arrives with this trough. Temperatures will 

initially stay mild Monday and Tuesday as the colder airmass remains 

to the north, supporting relatively high snow levels at 

approximately 7000 feet or higher. A prominent and windy cold front 

is forecast to move through east Oregon and southwest Idaho Tuesday 

evening into Wednesday. This front will be accompanied by a potent 

atmospheric river plume, spreading notable precipitation across the 

region. Max temperatures will drop by approximately 10 degrees for 

Wednesday, with snow levels also lowering to 3500-4500 feet MSL. 

While precipitation will become likely area-wide, this flow will 

most favor the higher terrain of west-central/central Idaho.



There remains considerable guidance uncertainty on the positioning 

of the polar jet stream beginning late Wednesday and beyond, which 

decreases forecast confidence in temperatures/snow levels for the 

rest of the week. However, ensembles suggest that a fairly 

persistent plume of Pacific moisture will continue to pummel the 

Pacific Northwest throughout the rest of the week. As a result, 

significant precipitation totals are possible across the mountains 

throughout next week, reaching over an 1" of new liquid equivalent 

over the west-central/central Idaho terrain. Depending on the 

oscillation of snow level during these series of moisture pushes, 

snowfall totals could reach 1 to 2 feet for higher elevations during 

this extended period.



&&





.AVIATION...VFR and mostly clear with few high clouds. Surface 

winds: mostly variable under 10 kt, except W-SW 10-15 kt in Magic 

Valley through the afternoon. Winds aloft at 10kft MSL: W-NW 20-35 

kt.



KBOI...VFR with clear skies. Surface winds: variable or briefly N-NW 

3-7 kt this afternoon/early evening.



Weekend Outlook...Mostly VFR with clear skies and some high clouds. 

Low stratus and patchy fog possible in sheltered valleys 

overnight/early morning on Sat/Sun. Light and variable winds.



&&





.BOI WATCHES/WARNINGS/ADVISORIES...

ID...Air Stagnation Advisory until 5 AM MST Monday 

     IDZ012-014-016-033.

OR...Air Stagnation Advisory until 5 AM MST /4 AM PST/ Monday 

     ORZ061>064.



&&



$$



www.weather.gov/Boise



Interact with us via social media:

www.facebook.com/NWSBoise

www.x.com/NWSBoise



SHORT TERM...JB

LONG TERM....JY

AVIATION.....JY