textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Heat Advisory continues today for lower elevations of southwest Idaho and southeast Oregon, extending through Monday evening for south-central Idaho.

- Breezy afternoon winds through the weekend. - Showers and thunderstorms return late Monday through Tuesday night with the arrival of monsoon moisture.

- Hot temperatures will last through the week, along with slight thunderstorm chances over the higher terrain each day.

SHORT TERM /Through Monday Night/

Issued 302 AM MDT SAT JUL 11 2026 Prevailing south-southwest flow aloft will bring another day of hot temperatures, dry conditions, and breezy winds this afternoon. Today is expected to be the hottest day of the entire forecast period, peaking at upper 90s to 106 for lower elevations. Consequently, a Heat Advisory remains in effect until 9pm MDT tonight for the Upper Weiser Basin, Snake Plain, and areas south to the NV border. The advisory will extend through Monday evening for south-central Idaho due to the continuation of moderate/major heat risk for that area.

Increasing high clouds today will keep overnight low temperatures relatively warm tonight, limiting heat-relief for lower elevations. Cloud cover and breezy winds will persist into Sunday, though a few degrees of cooling can be expected for most areas as the strong high pressure shifts slightly toward the east. By Monday, an influx of mid-level monsoonal moisture will boost precipitable water values to around 1.00", triggering showers and thunderstorms primarily over higher terrain in the afternoon and evening. With unstable conditions and hot surface temperatures in place, convective activity will pose a threat of gusty outflow winds, heavy downpours, and cloud to ground lightning.

LONG TERM /Tuesday through Saturday/

Issued 302 AM MDT SAT JUL 11 2026 Mid-level monsoonal moisture will continue streaming in from the south on Tuesday, maintaining PWAT values at or above 1.00". This will enhance shower and thunderstorm coverage across southeast Oregon and southwest Idaho by Tuesday afternoon. Heavy downpours are likely with stronger convection, along with gusty, rain-driven cold pools as low-levels moisten further. Late Tuesday into Wednesday, an incoming Pacific trough will move inland, nudging the bulk of the monsoonal moisture eastward by Wednesday. As a result, storm chances will decrease for Wednesday and Thursday, though higher terrain (primarily in SW Idaho) remains susceptible to convective development both days. Despite the eastward shift of the high pressure center, temperatures will remain hot all week...hovering around 5 degrees above normal. While model guidance begins to diverge toward the end of the week regarding moisture placement, a slight chance of showers and thunderstorms remains over higher terrain. Models stay in general agreement that hot southwest flow aloft will dominate through at least Friday/Saturday.

AVIATION /12Z Saturday through Sunday/

Issued 532 AM MDT SAT JUL 11 2026

VFR with increasing high clouds this afternoon. Areas of reduced visibility from wildfire smoke/haze. High density altitude due to heat. Surface winds: variable 5-15 kt through morning, becoming SE-SW 5-15 kt in the afternoon. Afternoon gusts to 20-30 kt, mainly over southeast OR and high terrain of southwest ID. Winds aloft at 10kft MSL: SW 15-30 kt.

KBOI...VFR with increasing high clouds this afternoon. Visibility reduced at times by wildfire smoke in foothills NE of KBOI. High density altitude due to heat. Surface winds: E-S 5-12 kt.

Sunday Outlook...VFR and BKN-OVC high clouds. Areas of reduced visibility from wildfire smoke/haze. High density altitude due to heat. Surface winds: SW-NW 5-15 kt with afternoon gusts to 20-25 kt. Except SW 10-20 kt with gusts 25-35 kt across SE Oregon late afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Heat Advisory until 9 PM MDT this evening for IDZ012-014-015- 033. Heat Advisory until 9 PM MDT Monday for IDZ016-030. OR...Heat Advisory until 9 PM MDT /8 PM PDT/ this evening for ORZ064.