textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Heat Advisory today and Saturday for lower elevations of southwest Idaho and southeast Oregon.

- 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 Sunday Night/

Issued 304 AM MDT FRI JUL 10 2026 Strong high pressure centered over the Desert SW will expand northward today through the weekend, positioning SW Idaho and SE Oregon in southwest flow aloft. Temperatures are expected to heat up in the lower valleys to upper 90s-105 degrees today and Saturday. Relatively warm overnight lows are also anticipated, resulting in minimal relief from heat. A Heat Advisory remains in effect across Weiser Basin, the western Snake Plain, and areas south to the NV border this afternoon through Saturday due to moderate/major Heat Risk levels. Meanwhile, surface winds will become breezy today through the weekend across southeast Oregon and (mainly) the higher terrain of SW Idaho as strengthening mid-level flow mixes to the surface. Temperatures will cool by a couple of degrees Sunday with an influx of high clouds, but heat impacts are expected to continue.

LONG TERM /Monday through Friday/

Issued 304 AM MDT FRI JUL 10 2026 Mid/high level moisture and precipitable water values will ramp up Monday and Tuesday as monsoon moisture makes its way north into the region. As a result, shower and thunderstorm chances increase starting Monday afternoon, favoring higher terrain. Initial convection will lean drier and outflow dominant from precedent dry low- levels, but should soon become heavier rain producers Tuesday into Wednesday as PWAT values reach 1.00"+ and low- levels moisten. Shower/thunderstorm chances will expand to most areas by Tuesday, though NBM/WPC guidance still struggles to resolve this transition despite the enhanced coverage in deterministic models. Meanwhile, a broad Pacific trough is forecast to move south along the West Coast Monday and Tuesday, but models disagree on when to bring the trough onshore and push monsoon moisture toward the east. The trough evolution will determine whether showers and thunderstorms continue through the rest of the week/next weekend, or gradually decrease around mid-week. Overall, southerly flow is expected to persist through Friday and support hot temperatures area-wide.

AVIATION /12Z Friday through Saturday/

Issued 457 AM MDT FRI JUL 10 2026

VFR. Areas of reduced visibility from wildfire smoke. High density altitude due to heat. Isolated convection over central ID mountains and south-central ID this afternoon. Surface winds: light and variable. Becoming SW-W 10-15 kt with gusts to 20-30 kt over SE Oregon and higher terrain of SW Idaho in the afternoon. Winds aloft at 10kft MSL: SW 5-15 kt.

KBOI...VFR. High density altitude due to heat. Visibility reduced at times by wildfire smoke in foothills NE of KBOI. Surface winds: SE-S 5-10 kt.

Weekend Outlook...VFR. Areas of reduced visibility from wildfire smoke. High density altitude due to heat, especially Saturday. Surface winds: SW-NW 5-15 kt Sat/Sun. Afternoon gusts to 20-30 kt across SE Oregon and (mainly) the higher terrain of SW Idaho.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Heat Advisory from noon today to 9 PM MDT Saturday for IDZ012- 014>016-030-033. OR...Heat Advisory from noon MDT /11 AM PDT/ today to 9 PM MDT /8 PM PDT/ Saturday for ORZ064.