textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Hot and windy this afternoon. - Cold front to pass through eastern Oregon Friday morning and western Idaho Friday afternoon. Front will bring gusty northwest winds, sharply cooling temperatures, and brief showers and isolated thunderstorms to northern and western areas.

- Mostly cloudy and cool Saturday and Sunday.

- Sunny and warmer Monday, then partly cloudy, breezy, and cooler Tuesday.

- Dry and gradually warmer Wednesday through Friday.

SHORT TERM /Through Saturday Night/

Issued 210 PM MDT THU SEP 24 2026 Mostly sunny, hot, and windy weather this afternoon under dry southwest flow aloft. A strong Pacific cold front just off the northwest coast today will move inland tonight, through our Oregon zones Friday morning, and Idaho zones Friday afternoon. The frontal passage will be marked by a wind shift from southeast to gusty northwest, followed by falling temperatures. Highs in eastern Oregon Friday will only be in the 60s to mid 70s, or 15 to 20 degrees cooler than today, while Idaho zones will have enough time to get into the 70s to mid 80s before the front arrives, with the remaining cooling coming on Saturday. This frontal system will be lacking in moisture, with showers and isolated thunderstorms occurring only briefly in northern- most areas just after the front passes. Southern areas will have increasing clouds but remain dry. Skies should clear for a few hours in eastern Oregon Friday night as the supporting upper trough moves out, but clouds will increase again overnight as another Pacific trough comes inland. Idaho will stay partly to mostly cloudy the whole time through Saturday. The clouds and lingering northwest winds will keep low temps from dropping way down Saturday morning, although Harney and Baker Counties will still manage to get below freezing. The second upper trough will keep our CWA partly to mostly cloudy and cooler than normal Saturday through Sunday. Models allow a slight chance of showers and thunderstorms in easternmost Idaho zones Sunday afternoon.

LONG TERM /Sunday through Thursday/

Issued 210 PM MDT THU SEP 24 2026 Monday looks sunny and warmer as the second upper trough moves out, but Tuesday looks windy and slightly cooler again as the next broad but shallow Pacific upper trough comes inland. Models are in wide disagreement after that with GFS steadily deepening the upper trough which would bring further cooling, while ECMWF moves the trough out which would bring warming. Our decision, based on NBM, is for gradual warming to normal while staying dry Wednesday through Friday.

AVIATION /00Z Friday through Saturday/

Issued 545 PM MDT THU SEP 24 2026

VFR. A cold front will bring gusty winds and ceilings to 5000 ft in eastern Oregon after Fri/15Z. LLWS expected at KMYL after Fri/06Z. Surface winds: S-SE 10-15 kt with gusts 20-25 kt, with strengthening SW-W winds with gusts to 30 kt after Fri/15Z. Winds aloft at 10kft MSL:SW 15-25 kt, becoming 25-45 kt Fri morning.

KBOI...VFR. Surface winds: SE 10-15 kt with gusts up to 25 kt through Fri morning. Cold front will move through Friday afternoon.

Weekend Outlook...Cold front passage Friday with gusty winds across the area. Rain band along the front passes north KBNO/KBKE/KMYL, but light rain and virga is possible Friday late morning and afternoon. Saturday will be partly cloudy and Sunday mostly cloudy as another system and isolated showers move through the area. Surface winds: W-SW 15-20 kt with gusts to 30 kt Friday, NW 5-15 kt Saturday, and NW 10-20 kt Sunday.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.