textproduct: Boise

KEY MESSAGES

- Hotter Friday.

- Scattered showers and thunderstorms late Friday through Saturday. Storms late Friday and Friday night could produce strong outflow winds and little rain, but storms Saturday will be wetter with locally heavy rain, especially over higher terrain in Idaho.

SHORT TERM /Through Saturday Night/

Friday looks 3-6 degrees hotter than today as a transitory upper ridge passes through the area. A Pacific trough will begin scattered thunderstorms in southeast Oregon early Friday afternoon, Harney County first, then Malheur County. Showers and chance of thunderstorms will advance eastward into Idaho south of the Snake Basin Friday night, then northeastward across remaining Idaho zones Saturday, as southeast Oregon begins to dry out. Initial thunderstorms in Oregon Friday will feature mainly gusty downdraft and outflow winds, with little rain, but storms Friday night and Saturday will trend wetter as they spread into southwest Idaho. Latest models target the Boise Mountains and West central Idaho mountains for heaviest rainfall on Saturday, possibly up to 0.50 inch. Thunderstorms should end by sunset Saturday and showers should end by midnight Saturday night. With clouds and showers around, Friday night will stay mild with lows in the 50s in the mountains to mid 60s in the valleys. But Saturday looks 10-15 degrees cooler than Friday as showers continue and the Pacific upper trough moves through our CWA.

LONG TERM /Sunday through Thursday/

The upper trough will steer out of the region Sunday, keeping the area under northwest flow and seasonal normal temperatures. Monday through the end of the extended period, a ridge of high pressure will build back over the northwest region, leading to a return of dry conditions and a steady warming trend through midweek. Tuesday and Wednesday are still expecting to see temperatures 10 to 20 degrees above normal. Come Thursday, a dry shortwave trough from the Pacific coast will dig across our area. There is considerable guidance uncertainty about this trough, but for now, a potential cooling trend with dry conditions will remain for Thursday.

AVIATION /18Z Thursday through Friday/

Issued 1147 AM MDT THU JUN 18 2026 VFR. SCT-BKN high clouds this afternoon. Surface winds: W-NW 5-15 kt, with gusts up to 20 kt near KMUO-KJER-KTWF this afternoon through sunset. Winds aloft at 10kft MSL: W-NW 15-25 kt.

KBOI...VFR with scattered high clouds this afternoon. Surface winds: NW 7-12 kt this afternoon, becoming variable under 7 kt this evening after sunset.

Weekend Outlook...Mostly VFR. Scattered MVFR showers and thunderstorms Friday afternoon through Saturday. The stronger storms could produce outflow winds gusts up to 45 kt, blowing dust, and brief heavy rain. Highest chances of heavy rain over central ID mountains on Saturday. Clearing skies Sunday with light winds.

FIRE WEATHER

A Red Flag Warning has been issued for lightning in southeast Oregon Friday afternoon and Friday night, specifically the Burns BLM (670) and Southern Grasslands (672), and for southwest Idaho Friday night through noon MDT Saturday, specifically The Owyhee Mountains (423) and southern Highlands (426). Thunderstorms in Oregon will feature mainly gusty outflow winds and little rain, but storms will trend wetter as they advance into southern Idaho Friday night and especially Saturday. Heavy thunderstorm rains are possible in Idaho Saturday, especially in the Boise NF and southern part of the Payette NF.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning from 6 PM Friday to noon MDT Saturday for IDZ423-426. OR...Red Flag Warning from 1 PM Friday to 5 AM PDT Saturday for ORZ670-672.