textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Hot weather expected through Independence Day holiday weekend.

- Slight chance of thunderstorms over central ID mountains, southeast OR, and far southwest ID late Sunday, with chances expanding area-wide Monday. - Hot and dry with periods of breezy conditions through next week.

SHORT TERM /Through Monday Night/

Issued 335 AM MDT SAT JUL 4 2026 An upper level ridge centered over the Southern Plains/Four Corners region will build north today and Sunday. The ridge and southwest flow aloft will bring hot temperatures to the area, with high temperatures increasing 5-8 degrees today and another couple of degrees on Sunday. This will place high temperatures in the mid to upper 90s in the lower elevations, with the hottest locations approaching 100 degrees on Sunday. In Boise, there is about a 30% chance of reaching triple digits. In the mountain valleys, highs will be in the 80s to lower 90s. Skies today will be mostly sunny with some afternoon cumulus over the higher terrain. However, there will be a stable layer aloft preventing further development into showers or thunderstorms. By Sunday, forecast soundings indicate this layer will be removed with an increase in mid-level moisture. This will allow for a 20% chance of showers and thunderstorms to develop over the higher terrain across southeast Oregon, far southwest Idaho, and the central Idaho mountains. Due to limited moisture, lightning and gusty outflow winds will be the primary threats, with gusts 40-60 mph possible. Outside of storms, expect breezy conditions across eastern Oregon this evening with gusts 20-35 mph, becoming more widespread Sunday.

A weak shortwave trough will move across the area Sunday night and Monday. The trough will continue a slight chance of showers and thunderstorms overnight across eastern Oregon and far western Idaho, with additional development on Monday afternoon across the higher terrain. The trough will also reduce high temperatures by 3-5 degrees and bring breezy conditions.

LONG TERM /Tuesday through Saturday/

Issued 335 AM MDT SAT JUL 4 2026 A 10-30% chance of showers and thunderstorms will continue into Tuesday over the higher terrain as enough moisture lingers under southwesterly flow. The flow aloft will transition to westerly Wednesday and Thursday as a trough moves by to the north, pushing moisture to the east. Additionally, winds will become breezy and by Thursday, temperatures will cool to around normal. For Friday into the weekend, the Four Corners high is expected to strengthen and build north while a trough deepens off the coast. Southwest flow will bring increasing temperatures and breezy conditions. Currently, ensembles slightly favor some influence from the trough, keeping temperatures in check. However, if the ridge builds further west, very hot temperatures would develop across the area over the weekend.

AVIATION /12Z Saturday through Sunday/

Issued 544 AM MDT SAT JUL 4 2026 VFR. A few cumulus over the higher terrain and along the Nevada border this afternoon and evening, otherwise clear skies. High density altitude in the afternoon/evening due to heat. Surface winds: variable 10 kt or less, becoming SW-NW 5-15 kt in the afternoon. NW gusts 15-25 kt KBKE to KONO this evening. Winds aloft at 10kft MSL: SW 10-20 kt.

KBOI...VFR under clear skies. Surface winds: SE 5-10 kt, then NW 7-12 kt in the afternoon, becoming variable less than 10 kt overnight.

Sunday Outlook...Mainly VFR. Isolated thunderstorms over SE Oregon, far SW Idaho, and the central Idaho mountains late afternoon and evening. High density altitude in the afternoon and evening due to heat. Gusty outflow winds from showers and thunderstorms up to 50 kt. Surface winds: W-NW 5-15 kt. NW gusts 20-30 kt KBKE to KONO and near KMUO in the evening.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.