textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Scattered showers and thunderstorms late today through Saturday.

- Daytime temperatures cooling to normal Saturday and Sunday, then hotter and drier Monday through Wednesday.

SHORT TERM /Through Sunday Night/

Issued 221 PM MDT FRI JUN 19 2026 As of 2 PM MDT thunderstorms were already developing along the NV/OR border and moving north. An upper trough in northern California tonight will move slowly ENE-ward across the northern Great Basin Saturday and into eastern ID and southwest MT Sunday. Shower and thunderstorm coverage will increase in southeast Oregon through this evening, and in southwest Idaho later tonight, continuing in both areas Saturday. Stronger storms will produce gusty outflow winds, especially in southeast OR late today and this evening. Storms should weaken during the overnight hours but become stronger again later Saturday. Low temperatures tonight will be warmer than normal, but highs Saturday and Sunday will be cooler than today, and close to normal for mid-late June. Lows Saturday night will be about ten degrees cooler than tonight but still slightly above normal. Lows Sunday night should be another 5-10 degrees cooler with clearer skies and drier air in place.

LONG TERM /Monday through Friday/

Issued 221 PM MDT FRI JUN 19 2026 A ridge of high pressure will build over the West Coast beginning Monday, bringing a warming and drying trend to the region through the middle of the week. Valley high temperatures will reach the upper 90s to low triple digits by Wednesday. A shortwave trough will then move into the region late Wednesday into Thursday. This will bring slight cooling, breezy valley winds, and a low chance of showers and thunderstorms over high terrain on Thursday/Friday. Model variance remains high on the strength of the trough and the extent of moisture, but the best agreement exists for precipitation to stay over eastern Idaho. Long range models hint at a stronger closed low to move into the Pacific Northwest by late Friday, which would bring much cooler temperatures and precipitation for the end of the week.

AVIATION /00Z Saturday through Sunday/

Issued 555 PM MDT FRI JUN 19 2026

Generally VFR. Widespread virga and isolated lightning, through this evening. Then, numerous rain showers and isolated thunderstorms overnight into Sat AM. Localized MVFR in rain. Activity capable of erratic outflows to 25-45 kt, and blowing dust. Surface winds outside of storms: W-NW 5-15 kt, then variable 10 kt or less overnight. Winds aloft at 10kft: westerly 5-20 kt.

KBOI...VFR. Virga, with 10% chance of light rain this eve through overnight period. Then, rain showers likely between Sat/12Z-21Z. Surface winds: SW-NW 5-15 kt, then variable less than 10 kt overnight. Threat of erratic outflow wind gusts to 25-35 kt from showers, mainly between Sat/06Z-09Z.

Weekend Outlook...Generally VFR. Scattered showers and thunderstorms Sat afternoon, favoring central ID and near NV border. Mountains obscured in precip. Storms capable of small hail, erratic outflows to 25-45 kt, blowing dust, and brief heavy rain/MVFR. Breezy SW-NW winds Saturday afternoon. Clearing skies Sunday with breezy NW-W winds through the Snake Plain.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning until 6 PM MDT Saturday for IDZ423-426. OR...Red Flag Warning until 5 PM PDT Saturday for ORZ670-672.