Marine Weather and Tide Forecast for Boise City, ID

KEY MESSAGES
- Warming trend will bring temperatures near to above 100 degrees by Thursday through the weekend.

- Breezy winds Friday through the weekend with very low precipitation chances returning along the ID/NV border.

- Smoky conditions continue through the week.

SHORT TERM /Through Friday Night/
Issued 353 AM MDT WED AUG 5 2026 Continued amplification of the Desert Southwest upper-level ridge is expected over the area through the short term. This will continue the trend of hotter and drier weather, with each consecutive day warming a few degrees from the previous day. By Friday afternoon, temperatures 100-105 are forecast to be widespread in elevations below 5000 ft MSL. Overnight minimum temperatures will also be a concern for these lower elevations, with reduced relief from temperatures only cooling to the mid 60s to even localized 70 degrees overnight. Localized dense smoke conditions could stand to temper these by a few degrees, but widespread heat impacts are expected Thursday and especially Friday. Speaking of smoke, continued effects are expected over the next few days. Air quality alerts are ongoing for Southeast Oregon and Southwest Idaho and are in effect until at least Thursday. Some mild improvement to smoke is expected each day as mixing occurs in the afternoon from diurnal heating and afternoon breeziness.

LONG TERM /Saturday through Wednesday/
Issued 353 AM MDT WED AUG 5 2026 Stronger westerly flow aloft will move into the area as upper- level troughing builds offshore and the Desert Southwest ridge flattens and weakens. While hot temperatures will continue, increased winds and the low possibility of precipitation return to the forecast. Current long range models keep the precipitation primarily in far southern ID & along the ID/NV border, which would manifest itself through afternoon thunderstorms. Precipitation chances generally increase day over day as monsoonal moisture is transported north. For now, it looks as though the rest of the Great Basin and Desert Southwest will receive the precipitation, but our region is on the cusp. Temperatures will be 5-10 degrees above normal with lower valleys near 100 degrees Saturday, decreasing to near normal / about 5 degrees above normal Sunday onward. Breezy winds and hot temperatures will create fire weather concerns.
Smoky conditions will continue from area wildfires which may keep temperatures slightly cooler than forecast.

AVIATION /18Z Wednesday through Thursday/
Issued 1231 PM MDT WED AUG 5 2026 Reduced visibility due to wildfire smoke, with areas of MVFR-IFR and mountain obscuration, otherwise low VFR. High density altitude during afternoon due to heat. Surface winds: variable 5-10 kt.
Winds aloft at 10kft MSL: W-NW 5-15 kt shifting to SW 5-15kt by 18z/Thu.

KBOI...low VFR due to wildfire smoke. Surface winds: NW 5-10kt becoming SE 5-10kt after sunset.

BOI WATCHES/WARNINGS/ADVISORIES
ID...Air Quality Alert until 2 PM MDT Friday for IDZ011>015-028-029- 033.
Heat Advisory from 2 PM Thursday to 9 PM MDT Saturday for IDZ012-014>016-029-030-033.
Air Quality Alert until 1 PM MDT Thursday for IDZ016-030.
OR...Heat Advisory from 2 PM MDT /1 PM PDT/ Thursday to 9 PM MDT /8 PM PDT/ Saturday for ORZ061>064.
Air Quality Alert until 1 PM MDT /noon PDT/ Thursday for ORZ061>064.