textproduct: Boise

KEY MESSAGES

- A cold frontal passage Saturday will bring cooler temperatures, light mountain showers, and gusty W-NW winds through the evening.

- Warm, slightly above normal temperatures will continue the middle of next week.

- Another cold front will move through the region by the middle of next week, bringing mountain showers and cooler temperatures.

SHORT TERM /Through Monday Night/

A weak cold front is continuing to push southeastward across the forecast area this evening. While the front is not well defined in surface observations, it is clearly demarcated by a developing cumulus field on satellite imagery. The primary impact has been elevated winds this afternoon and evening, with wind gusts reaching up to 40 mph in wind-prone areas. Precipitation chances remain low as the deepest moisture stays to our north, though a 10 to 20 percent chance of light rain showers will continue for northern portions of Baker and Valley counties through tonight.

The ridge begins to build back over the area on Sunday. This will shift the cooler zonal flow further north, keeping our region dry. Temperatures will remain above normal through the period. By Monday night, an atmospheric river associated with a low off the British Columbia coast will begin to approach the Pacific Northwest. While this system will attempt to push moisture and colder air into the region, it will face resistance from the persistent ridge over the Desert Southwest. Guidance today continues to trend warmer and drier; consequently, any precipitation through Monday night is expected to remain light and confined mostly to the higher terrain of Baker County and the mountains of southwest Idaho.

LONG TERM /Tuesday through Saturday/

The large upper level ridge over western US the will flatten out a bit allowing a more zonal west to east upper level flow to bring moisture into the area on Tuesday and Wednesday. The best chances for precipitation will be across the northern half of our forecast area where a 50 to 60 percent chance of rain exists. The southern half of the forecast area will remain dry. The zonal flow pattern should allow temperatures to cool down a bit Wednesday through Thursday, though still remaining above 5 to 10 degrees above normal. Most models show the ridge beginning to rebuild over the western US again by Friday and continue that pattern into the weekend. The forecast for southwestern Idaho and southeastern Oregon responds to that scenario and shows a warming trend starting on Friday with dry weather.

AVIATION /18Z Saturday through Sunday/

Issued 1205 PM MDT SAT MAR 21 2026 A cold front extending from KMYL to KBNO at 18Z is moving southeastward. A band of clouds with MVFR ceilings and some mountain obscurations are associated with the front. Otherwise VFR conditions prevail across the rest of southwestern Idaho and southeastern Oregon. Winds are light and variable ahead of the front and will shift to NW 15 to 20 kts behind the front. Winds aloft at 10K feet: W 25 to 30 kts.

KBOI...VFR. Surface winds NW at 5 to 10 kts, increasing to 10 10 to 15 kts after 20Z.

Sunday Outlook...Mostly VFR condition expected across southwestern Idaho and southeastern Oregon. Surface winds W to NW 10 to 15 kts. Winds aloft at 10K feet: W 25 to 30 kts.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.