textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Isolated showers and thunderstorms this afternoon over higher terrain, with gusty outflows up to 35 mph.

- Temperatures near or slightly above normal through mid-week, then heat amplifying for Thursday and Friday.

- Return of monsoon moisture Friday into the weekend will increase shower and thunderstorm chances once again.

SHORT TERM /Through Wednesday Night/

Issued 205 PM MDT MON AUG 17 2026 A distinct line of very light showers is currently pushing north over the Treasure Valley and Malheur County, with minimal precipitation amounts observed as of 2pm MDT. Cloud cover will continue to persist through the evening, with a weak shortwave trough moving through the region this afternoon. This will continue the 10-20% chance of showers and thunderstorms, primarily over the central ID mountains and near the high terrain over the NV-ID border. The primary hazards with any of these thunderstorms will be gusty outflows up to 35 mph and lightning. Thunderstorm potential is slightly lower than previously forecast due to the widespread persistent cloud clover this afternoon. Lingering moisture over eastern Valley County tomorrow will keep a 5-10% chance of showers and thunderstorms through the evening. High pressure will build back in over the Intermountain West tomorrow through the end of the short term period, bringing a steady warming and drying trend with generally light winds. Smoke from Oregon/Washington wildfires will filter into the region tomorrow, with the thickest smoke over Baker County, OR.

LONG TERM /Thursday through Monday/

Issued 205 PM MDT MON AUG 17 2026 The Four Corners upper-level ridge will continue to build Thursday and Friday with the Pacific low pressure system slowly moving towards the shore. Southwesterly flow aloft will transition to increased southerly winds through much of the weekend. This pattern will bring back summertime heat risk, with temperatures climbing to near 100 degrees for lower elevations. Precipitation chances will start isolated in the higher terrain of SW Idaho Thursday, increasing to most higher elevations across SW Idaho and SE Oregon Friday. Afternoon wind gusts will also become breezier late week into the weekend. The upper-level trough will move onshore late Friday into Saturday and quickly move NE through the Pacific NW and Northern Rockies. Cooling temperatures to near-normal are forecast Saturday and Sunday with this disturbance moving through.

AVIATION /00Z Tuesday through Wednesday/

Issued 517 PM MDT MON AUG 17 2026 VFR. Weak, isolated showers/thunderstorms continuing through this evening over west-central ID mtns and near KTWF/KJER. Erratic outflows to around 35 kt possible in storms. Patchy surface smoke near KBKE/KBNO tonight through Tuesday morning. Surface winds: variable or NW 5-10 kt this evening, becoming mostly light and variable overnight. Winds aloft at 10kft MSL: W 5-15 kt.

KBOI...VFR. Possible storm outflows to 30 kt this evening through sunset. Surface winds: NW-N 5-10 kt, then variable under 7 kt tonight after sunset.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.