textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Heat Advisory 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 the week, with peak coverage on Tuesday.

- Hot temperatures remain through the week.

SHORT TERM /Through Tuesday Night/

Issued 208 PM MDT SAT JUL 11 2026 A Heat Advisory remains in effect today as temperatures in the Snake Plain, Weiser Basin, and Southwest Highlands of Idaho reach max temperatures in the upper 90s and lower 100s. The south-southwest flow across the region will make it a very hot day even outside the heat advisory. Clouds tomorrow will moderate temps for the lower elevations to the mid 90s, except in the upper Snake Plain near the Magic Valley where temps will approach 100 degrees for a second day. The Heat Advisory in the Magic Valley will continue through Sunday as a result.

The increasing clouds are the first hint at more moisture flux into the region due to the broader circulation around the central Rockies. This flow is injecting warm moisture from the Pacific and Gulf of California. The heat, moisture, and latent instability will be enough to kick off isolated dry thunderstorms late Monday afternoon and evening. Especially in Southeast Oregon, far Southwest Idaho, and Central Idaho mountains. Thunderstorms will be capable of gusty outflow winds and heavy downpours.

LONG TERM /Wednesday through Sunday/

Issued 208 PM MDT SAT JUL 11 2026 Southerly/southwesterly flow aloft will be maintained throughout the long term period as consistent upper-level troughing will be off the Pacific NW coast and upper-level ridging will remain cemented in the central CONUS. Consequently, mid and high-level monsoonal moisture will stream into the area, bringing PWAT values at or above 0.8" in lower elevations and at or above 0.6" in higher elevations through the period. The strongest push of moisture happens Tuesday, with PWAT values over 1.00" in lower elevations and above 0.8" in higher elevations (above 90th percentile climatology with localized spots higher than 95th percentile). This will enhance shower and thunderstorm coverage across southeast Oregon and southwest Idaho by Tuesday afternoon, with greater uncertainty for exact moisture placement Wednesday onward. Heavy downpours are likely with stronger convection, along with gusty, rain-driven cold pools as low-levels moisten further. Greatest concern will primarily be flash-flood potential Tuesday and Wednesday (especially over burn scars).

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 /06Z Sunday through Monday/

Issued 1228 AM MDT SUN JUL 12 2026

VFR with increasing high clouds and a 10% chance of light rain in E Oregon this PM. Areas of reduced visibility from wildfire smoke/haze. High density altitude due to heat. Surface winds: NW or variable 5-12 kt through morning. Valley gusts 20-30 kt between KBKE-KONO through Sunday morning. Winds aloft at 10kft MSL: S-SW 15-30 kt.

KBOI...VFR with increasing high clouds. Visibility reduced at times by wildfire smoke in foothills NE of KBOI. High density altitude due to heat Sunday afternoon/evening. Surface winds: W to NW 5-15 kt. Afternoon gusts around 20 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Heat Advisory until 9 PM MDT Monday for IDZ016-030. OR...None.