textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Hot temperatures through the week, potentially becoming very hot next weekend.

- Isolated to scattered showers and thunderstorms today through Tuesday mainly over higher terrain, with lightning, gusty outflow winds, brief heavy rain, and small hail possible. - Breezy winds each afternoon.

SHORT TERM /Through Tuesday Night/

Issued 354 AM MDT SUN JUL 5 2026 Another hot day is in store across our area today as a ridge of high pressure centered to our east strengthens and the flow aloft becomes southerly. Highs in most areas will be a couple degrees warmer than yesterday, with lower elevations reaching the mid to upper 90s and mountain valleys in the 80s to lower 90s. The southerly flow will also bring in mid-level moisture into our area, primarily across southeast Oregon ahead of a shortwave trough lifting north out of western Nevada. Increased moisture and the trough will bring isolated to scattered showers and thunderstorms to southeast Oregon and the Owyhee Mountains of southwest Idaho late this afternoon and evening. Due to limited moisture and dry low-levels, the primary hazards will be lightning and gusty outflow winds to 50 mph. Outside of storms, expect breezy afternoon and evening winds with gusts 20-35 mph.

Isolated to scattered showers with embedded thunderstorms will expand into southwest Idaho Sunday night into Monday morning as the trough moves across our area. Activity will increase in the afternoon across the west-central Idaho mountains near the center of the trough. Enough moisture will linger across the higher terrain of southeast Oregon and far southwest Idaho for additional afternoon/evening showers and thunderstorms. Slightly deeper moisture in place on Monday will allow for brief heavy rainfall and small hail in stronger storms, in addition to lightning and gusty winds. Highs Monday will cool 3-5 degrees behind the trough with continued breezy conditions. On Tuesday, temperatures will rebound under southwesterly flow aloft. Daytime instability will bring a 10-30% chance of showers and thunderstorms to the higher terrain.

LONG TERM /Wednesday through Sunday/

Issued 354 AM MDT SUN JUL 5 2026 An upper trough moving by to our north will bring westerly flow aloft Wednesday and Thursday. This will push moisture to the east, ending the threat for showers and thunderstorms after Wednesday. Expect breezy conditions with temperatures cooling a few degrees by Thursday. For Friday into the weekend, a ridge over the Four Corners will 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, moderating temperatures somewhat. However, if the ridge builds further west, very hot temperatures would develop across the area over the weekend, with highs over 100 degrees across lower elevations.

AVIATION /12Z Sunday through Monday/

Issued 541 AM MDT SUN JUL 5 2026 Mainly VFR. Isolated thunderstorms over SE Oregon, far SW Idaho, and the central Idaho mountains late this afternoon and evening. Thunderstorms capable of producing outflow gusts up to 45 kt. High density altitude this afternoon/evening due to heat. Surface winds: W-NW 5-15 kt, with gusts 15-30 kt late this afternoon and evening across southeast Oregon and the Snake River Plain. Winds aloft at 10kft MSL: S-SW 10-20 kt, becoming variable after Mon/00Z.

KBOI...VFR under clear skies this morning. Increasing high clouds this afternoon/evening. High density altitude this afternoon/evening due to heat. Surface winds: variable less than 10 kt this morning, becoming NW 7-12 kt with gusts up to 20 kt this afternoon.