textproduct: Boise

KEY MESSAGES

- Heat Advisory Friday 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 Saturday Night/

A broad upper level high pressure centered over the Rocky Mtns will expand into the region Friday and Saturday. The resulting warming will push temperatures to around 100 degrees across lower elevations, to include the Snake Plain and Weiser River basin. After Friday's heat, warm overnight lows Friday night will limit recovery for those without a way to cool down. The heat peaks on Saturday with much of the Advisory area reaching 100-103, while locations around Glenns Ferry push to 105. Winds will pick up some Friday afternoon, with the heat low enhancing the evening wind push through Baker County. Saturday will see broader coverage of breezy conditions as increasing southwest flow aloft mixes to the surface.

LONG TERM /Sunday through Thursday/

Continued hot through the period (4 to 8 degrees above normal) under high pressure aloft to our east encompassing the entire Great Basin, Rocky Mountains, and northern Plains states. An upper trough in the Gulf of Alaska will bring gradual cooling Tuesday through Thursday as it moves onto the northwest coast. Southwest flow aloft will transport mid and high level monsoon moisture over Oregon Monday and Tuesday, and Idaho Tuesday and Wednesday, for a slight chance of thunderstorms, with initial storms bringing gusty winds and little rain, and later storms being wetter, especially Wednesday, as PWAT values climb to 1.00-1.20 inch (i.e., 95th percentile relative to climatology). Concern will gradually shift from fire danger Monday and Tuesday due to lightning on dry fuels, to flash-flood potential by Wednesday.

AVIATION /18Z Thursday through Friday/

Issued 1117 AM MDT THU JUL 9 2026 VFR. Areas of reduced visibility 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 09/20Z until 10/00Z. Winds aloft at 10kft MSL: S-W 5-15 kt.

KBOI...VFR. High density altitude due to heat. Visibility reduced at times by wildfire smoke in foothills N and NE of KBOI. Surface winds: W-N 5-12 kt. Gusts 15-20kt 09/20Z until 10/00Z.

Weekend Outlook...VFR. Areas of reduced visibility from wildfire smoke. Isolated convection over central ID mountains Friday. High density altitude due to heat, especially Saturday. Surface winds: SW-NW 5-15 kt Friday through Sunday. Afternoon gusts to 20-30 kt across E Oregon and the Snake Basin in SW Idaho south to the ID/NV border.

BOI WATCHES/WARNINGS/ADVISORIES

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