textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Colder today but much less windy than yesterday.

- Warm front will bring a dusting of snow to northern mountains late tonight and Monday morning.

- Strong warming trend Monday and Tuesday, with widespread record high temperatures and dry conditions Tuesday through Saturday.

SHORT TERM /Through Tuesday Night/

Issued 326 AM MDT SUN MAR 15 2026 Yesterday's windstorm and cold front have passed, leaving a much colder air mass over our CWA this morning. Cold air will continue through tonight but much calmer than yesterday. High temps today will be about 15 degrees lower than yesterday in south-central Idaho, and 5 to 10 degrees lower than yesterday in Harney County/OR where cooling was already underway. A warming trend will begin in our CWA tonight, and Monday will be about 15 degrees warmer than today, with Tuesday another 7 to 10 degrees warmer. Record high temps are expected as early as Tuesday in southeast Oregon, with near-record highs in southwest Idaho, with even further warming to follow. The warming will be due to an exceptionally strong upper ridge building inland from the Pacific. A warm front will start the process with a dusting of snow late tonight and Monday morning in northern-most mountains of our CWA. The real warming will begin Monday after the warm front moves out. Monday afternoon will be breezy in the Snake Basin and southwest Idaho Highlands with speeds 15 to 25 mph, and gusts to 30 mph, but Tuesday will be calmer. Skies will be mostly clear in southern areas and partly cloudy in the north behind the warm front.

LONG TERM /Wednesday through Sunday/

Issued 326 AM MDT SUN MAR 15 2026 An upper-level ridge will continue to build over the western CONUS. This ridge will be unusually strong for this time of year, producing temperatures that will threaten or break daily warm temp records through much of the long-term. Wednesday through Saturday, temperatures will be 20-25 degrees warmer than normal. Many lowland areas will see afternoon highs in the upper 70s to lower 80s, while mountains stay in the upper 50s to lower 60s. The warm temperatures come alongside mild winds, partly cloudy skies, and dry afternoon relative humidity values ranging 20-30% in valleys and 30-50% in mountains.

Some relief is beginning to work into the 7-day forecast, as Sunday's synoptic pattern features an Alaskan low that drifts south. While the core of the low remains near Juneau, that southward drift will push the jet stream and colder heights overhead. This will lead to an increase in winds, and more notably a cooling trend set to continue past the long term. Ensemble member spread increases significantly on Sunday at the start of this cooldown, with a temperature forecast spread of 20 degrees. The warmest members still show a steady cooldown, however, so even if Sunday is warmer than forecast there is high confidence in the cooling trend setting in.

AVIATION /18Z Sunday through Monday/

Issued 1118 AM MDT SUN MAR 15 2026 VFR with increasing mid and high clouds through the day. A weak frontal system may bring the chance for showers for northern terminals, including BKE and MYL, after 02Z. Brief MFR/IFR conditions will be possible in the showers through 06/07Z. Surface winds less than 10 kt, except WNW 10-15 kt with gusts to 25 kt possible in the Magic Valley of Idaho. Winds aloft at 10kft MSL: NW 10-30 kt.

KBOI...VFR with increasing clouds and ceilings approaching 5000/6000 ft 02-11Z. Surface winds light then becoming WNW less than 10 kt after 18Z, then SE less than 6 kt after 02Z.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.