textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Hot and dry, with breezy afternoon winds through the weekend. - Shower and thunderstorm chances return early next week with the arrival of monsoon moisture.

SHORT TERM /Through Saturday Night/

Issued 324 AM MDT THU JUL 9 2026 A few degrees of cooling with northwest surface winds are expected today behind Wednesday's weak cold front. Hi-res models indicate storm activity this afternoon should remain south of the Idaho border and east of Banner Summit in central Idaho, but outflows up to 40 mph may travel into the SW Idaho Highlands this evening. Beginning Friday, high pressure across the Desert Southwest is forecast to build north into the N Rockies, introducing a rapid onset of heat as south-southwest flow develops over the forecast area. This flow will generate breezy southwest surface winds across much of SE Oregon and the mountains of SW Idaho Friday afternoon. Latest model guidance places lower valley temperatures around 100 degrees, with mountain valleys in the 80s/90s. Temperatures will remain hot on Saturday, with lower valleys peaking in the upper 90s to 105 degrees. Overnight/morning temperatures will also remain warmer than normal, reducing the opportunity for heat-relief and increasing Heat Risk across the Snake Plain and south to the NV border on Saturday.

LONG TERM /Sunday through Thursday/

Issued 324 AM MDT THU JUL 9 2026 Slight cooling is anticipated from west to east on Sunday as a Pacific trough approaches the PNW coast. Temperatures will still remain hot, however, as deep south-southwest flow persists from the ridge dominating to the east. Cloud coverage is forecast to increase Sunday and Monday as mid/high level monsoon moisture makes its way north into the region. Precipitable water values will begin to ramp up significantly by late Monday, reaching 1.00"+ by Tuesday and Wednesday. As a result, the chance of showers and thunderstorms will increase through mid-week as the influx of moisture continues. While storms may initially be anemic and produce gusty outflows early in the week, storms will evolve into heavy rain producers if PWATs climb near/above 1.00". Max temps will hover at 5-10 degrees above normal through the week.

AVIATION /12Z Thursday through Friday/

Issued 512 AM MDT THU JUL 9 2026

VFR. Localized terrain obstruction from wildfire smoke. High density altitude due to heat. Surface winds: W-NW 5-15 kt, with gusts 20-25 kt from KMUO to KTWF/KJER. Winds aloft at 10kft MSL: S-W 5-15 kt.

KBOI...VFR. High density altitude due to heat. Foothills may be obscured at times due to nearby wildfire smoke. Surface winds: W-N 5-12 kt. Afternoon gusts to 15-20 kt.

Weekend Outlook...VFR. Localized visibility reductions in the vicinity of wildfires. Isolated convection over central ID mtns Friday. High density altitude due to heat, esp Saturday. Surface winds: SW-NW 5-15 kt Friday through Sunday. Afternoon gusts to 20-30 kt mainly across E Oregon and the higher terrain of SW Idaho.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.