textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Cooler, breezy, and drier through the weekend, except showers persisting over the central Idaho mountains.

- Temperatures warming to around 5-10 degrees above normal next week.

- Breezy Wednesday and Thursday with a 20-40% chance of showers and thunderstorms across the north.

SHORT TERM /Through Monday Night/

Issued 308 AM MDT SAT MAY 30 2026 An upper low will move northeast into Wyoming today and continue north into Montana by Sunday, then merge with a trough over the Pacific Northwest on Monday. The main impact from the low will be breezy conditions today and Sunday with gusts 20-30 mph, except up to 40 mph in the Snake Plain east of Mountain Home. Winds will subside on Monday. Most areas will be dry as the low pulls away, except the central Idaho mountains which will see a 20-50% chance of showers and embedded thunderstorms this afternoon and a 20% chance on Monday. Temperatures will be coolest today, generally 3-7 degrees below normal. High temperatures will rise a couple degrees on Sunday, then around 5 more degrees on Monday. Low temperatures will be cool through the period, with 40s in the lower valleys and 30s in the mountains.

LONG TERM /Tuesday through Saturday/

Issued 308 AM MDT SAT MAY 30 2026 High pressure will build overhead on Tuesday, increasing temperatures by around 5 degrees from Monday. On Wednesday, an upper level trough will approach and move through late in the day into Thursday. Highs are forecast to warm a few more degrees before the arrival of the trough, reaching around 10 degrees above normal. Temperatures will cool slightly Thursday behind the trough. The center of the trough is favored to move across northern areas, bringing a 20-40% chance of showers and thunderstorms to Baker County and the west-central Idaho mountains. Elsewhere, precipitation chances will be lower. Breezy conditions will develop across the area with the passage of the trough. On Friday, southwest flow aloft ahead of a deep upper level trough approaching the Pacific Northwest will bring warmer temperatures and continued breezy conditions. This trough is expected to move inland over the weekend, although there are timing and strength differences between ensemble members. For now, the forecast trends cooler on Saturday with a 10-20% chance of showers across the north.

AVIATION /12Z Saturday through Sunday/

Issued 550 AM MDT SAT MAY 30 2026 Mainly VFR. Scattered showers and isolated thunderstorms this afternoon over the central Idaho mountains, including near KMYL. Low clouds and brief periods of mountain obscuration in showers. Surface winds: W-NW 10-20 kt with gusts 20-30 kt, except up to 35 kt in the Magic Valley, decreasing to 5-15 kt by mid evening. Winds aloft at 10kft MSL: W-NW 15-30 kt.

KBOI...VFR. Surface winds: NW 10-15 kt, gusts to 25 kt developing by mid morning, decreasing after sunset.

Sunday Outlook...VFR. Patchy mountain valley fog in the morning. A few low clouds persisting over the central Idaho mountains. Surface winds: W-NW 5-15 kt with afternoon gusts 15-25 kt, except 10-20 kt with afternoon gusts to 30 kt in the Snake Plain east of KBOI.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.