textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Warm and mostly dry today ahead of a strong cold front late tonight with scattered showers, isolated thunderstorms, high elevation snow, and gusty westerly winds.

- Breezy and much cooler Sunday, with lingering showers in northeast OR and the central ID mountains.

- Unsettled cool conditions through the middle of next week, then a warming and drying trend likely for the weekend.

SHORT TERM /Through Monday Night/

Issued 216 PM MDT SAT SEP 12 2026 A strong low pressure system will move into the area this evening, with an associated cold front putting an end to the warm and dry conditions we'll see most of the day. Ahead of the front, this evening most of the high desert will see peak wind gusts 25 to 35 mph out of the southwest. Late this evening, as the front begins to track through Southeast Oregon, precipitation chances increase near the Blue Mountains, and wind gusts along ridges and highlands increase to 30 to 45 mph. Inside scattered showers, an isolated weak thunderstorm is possible. The front, winds, and precipitation move into southwest Idaho overnight. Thunder chances mostly subside overnight while gusts up to 45 mph remain possible along the highest ridges. Precipitation stays mostly north of our area, with only a 10- 20% in northern Valley County. The rainfall forecast continues to trend downwards, but with ~0.1 inches still possible in the Blue Mtns and Mtns north of McCall. Temperatures will drop for Sunday by about 15-20 degrees, with snow levels dropping down to 6,500-7,500 feet MSL. Minimal snow will fall over higher terrain, with accumulations of less than an inch primarily over the Wallowa/Seven Devils Mountain Ranges. Troughing will continue through Monday, with cool conditions lingering. Patchy valley fog will form in mountain valleys on Sunday and Monday morning.

LONG TERM /Tuesday through Saturday/

Issued 216 PM MDT SAT SEP 12 2026 A broad trough remains in place over the region. This will allow a weak upper level trough and accompanying dry cold front to cross the area. Limited moisture will keep precipitation chances near zero, but the frontal passage will generate breezy conditions, especially across the Snake River Plain and high terrain. High temperatures on Tuesday will remain slightly below seasonal normals behind the front.

By Wednesday, an upper level ridge begins building over the Intermountain West. Heights and temperatures aloft will steadily increase through the end of the week, yielding a clear warming and drying trend from Wednesday through Saturday. Temperatures will rise to 5 to 10 degrees above normal by Friday and Saturday. Model guidance shows high confidence in stable conditions under the ridge, with light diurnal winds and minimal cloud cover prevailing across the region through the remainder of the period.

AVIATION /06Z Sunday through Monday/

Issued 1134 PM MDT SAT SEP 12 2026

Mainly VFR. Cold front moving eastward overnight with showers across eastern Oregon and w-central ID. 10% chance of lightning in eastern Oregon through 13/08Z. Localized MVFR and mountain obscuration in showers. Lingering clouds but no precipitation on Sunday. Surface winds: W to NW 5-15 kt, with gusts to 25-30 kt early Sunday in eastern Oregon and southern Idaho. Winds aloft at 10kft MSL: SW 25- 45 kt.

KBOI...VFR with BKN mid-level clouds. Surface winds: WNW 10-15 kt with gusts to 25 kt after 20z/Sun.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.