textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Warmer and decreased wind Monday with temperatures rising to near normal.

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

- Breezy Wednesday and Thursday with shower and thunderstorm potential across the north.

SHORT TERM /Through Tuesday Night/

Issued 221 PM MDT SUN MAY 31 2026 An upper level low over Montana will slowly move northeast into southern Canada by Monday night and Tuesday. The forecast area will generally remain dry as the low pulls away but on Monday, a weak trough from the Pacific Northwest will move across our area and merge with the Montana low. This will introduce a 10-20% chance of showers and thunderstorms to the central Idaho mountains, mainly over eastern Valley County, and the upper reaches of the Boise River Basin. Temperatures will increase up to 5 degrees on Monday with the upward trend in temperatures continuing on Tuesday as a weak upper level ridge moves over the forecast area. Winds will be lighter Monday and Tuesday.

LONG TERM /Wednesday through Sunday/

Issued 221 PM MDT SUN MAY 31 2026 Daytime temperatures will continue to warm to about 10 degrees above normal Wednesday as southwest flow develops ahead of a weak, Pacific trough. The trough and accompanying cold front are forecast to arrive late Wednesday, introducing shower and thunderstorm chances across northern Harney and Malheur Counties, and Baker County, and west-central Idaho Wednesday into Thursday. Winds will become breezy behind the cold front on Thursday, with temperatures lowering by several degrees. Dry and warming conditions will develop once again Friday ahead of the next Pacific trough expected for the weekend. This system will support stronger wind gusts for both Saturday and Sunday as it tracks east through Oregon and Idaho. Models currently disagree on shower/thunderstorm development, but the arrival of the cold front late Saturday will ensure much cooler temperatures by Sunday.

AVIATION /06Z Monday through Tuesday/

Issued 1132 PM MDT SUN MAY 31 2026

VFR and high clouds. Cumulus buildups and isolated, weak rain showers over west-central Idaho Monday PM. Surface winds: variable 10 kt or less overnight, then W to NW 5-15 kt Monday PM. Afternoon gusts around 20 kt from KBOI to KJER/KTWF. Winds aloft at 10kft MSL: westerly 5-15 kt.

KBOI...VFR and high clouds. Surface winds: variable 6 kt or less, then NW 5-12 kt with occasional gusts to 15-20 kt Monday afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.