textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Slightly warmer Sunday, but continued cool and drier with breezy conditions across the Magic Valley area.

- 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 219 PM MDT SAT MAY 30 2026 An upper low centered over western Wyoming will move north into Montana tonight and Sunday, then merge with a trough over the Pacific Northwest on Monday. The main impact from the low will be breezy west-northwest winds through early this evening and again on Sunday, although winds aren't expected to be as strong Sunday. Winds will subside on Monday. Most areas will be dry as the low pulls away, except the eastern half of Valley County and headwaters of the Boise River Basin which will see a 20-50% chance of showers and embedded thunderstorms late this afternoon and a 20-30% chance on Monday. It will remain cool the rest of the weekend but high temperatures will trend up 1-3 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 219 PM MDT SAT MAY 30 2026 Temperatures will continue to rise Tuesday and Wednesday from high pressure building in aloft from upper-level shortwave ridging. This will be short lived, as another upper-level shortwave trough will move through Wednesday afternoon into Thursday afternoon. The potent area of this trough is favored to move across our 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. Highs are forecast to warm a few degrees before the arrival of the trough, reaching 5-10 degrees above normal. Temperatures will cool slightly (back to near-normal temps) Thursday behind the trough.

On Friday, significant cluster disagreement exists for an incoming intense upper-level low moving down the Pacific NW coast. GEFS members cluster around stronger southwest flow aloft, while the EC ensemble is closer to zonal/weaker southwest flow. Regardless of the solution, warmer temperatures and continued breezy conditions are expected. This trough is expected to move inland over the weekend, although there are similarly 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 /00Z Sunday through Monday/

Issued 558 PM MDT SAT MAY 30 2026 Mainly VFR. Areas of mountain obscuration NE of KMYL. Surface winds: W-NW 10-20 kt with gusts 20-30 kt, except up to 35 kt near KJER KTWF, decreasing to W-NW 5-15 kt after sunset. Winds aloft at 10kft MSL: W-NW 20-30kt easing to 10-20 kt Sun afternoon.

KBOI...VFR. Surface winds: NW 10-15 kt, gusts to 25 kt decreasing to NW 5-10kt after sunset.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.