105 FXUS65 KBOI 081539 AFDBOIArea Forecast Discussion National Weather Service Boise ID 939 AM MDT Wed Oct 8 2025
.DISCUSSION...Unseasonably warm conditions are expected today and Thursday, with temperatures running about 10 to 12 degrees above normal. Increasing southwesterly flow aloft, in response to a developing low-pressure system off the Pacific Northwest coast, should help boost surface winds from the south-southeast today. This flow regime will aid high temperatures in reaching the upper 70s today and the low 80s on Thursday, while maintaining mild low temperatures overnight. Clouds will increase later on Thursday, and the threat for showers will begin on Friday with the passage of a cold front. Until then, expect early fall-like conditions across the forecast area. No updates are needed at this time.
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.AVIATION...Mostly VFR. MVFR/IFR in sheltered mtn valleys with fog/low stratus. Clearing to VFR by 17z. LLWS developing early Thu morning. Surface winds: E-SE 5-15 kt with gusts to 25 kt in the Snake Plain. Winds aloft at 10kft MSL: SW 15-25 kt
KBOI...VFR and clear. LLWS possible early Thu morning. Surface winds: SE 10-15 kt with gusts up to 25 kt this afternoon.
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.PREV DISCUSSION... SHORT TERM...Today through Friday night...An upper level trough near Haida Gwaii will gradually move south along the coast through Thursday, shifting the flow aloft to the southwest and bringing warmer temperatures to the region. Southwest- southeast winds and will gradually increase through Friday ahead of the cold front. Temperatures Wednesday warm around 5 degrees and a few more degrees by Thursday. As the system moves south along the coast, high clouds increase across central OR. Thursday is likely the warmest day of the period for eastern OR while Friday is forecast to be the warmest day of the period for southwest Idaho. The trough becomes a closed low and remains off the OR coast, with a dry slot developing over southeast OR and southwest ID for much of the day Friday before a cold front arrives Friday evening. Showers chances increase to 20-40 percent late in the evening. With pronounced southwest flow continuing, favored areas for upslope flow will receive the brunt of the moisture, such as the west-central Idaho and Boise Mountains (60-80% chance).
LONG TERM...Saturday through Wednesday...The trough moves inland by Saturday, with showers increasing to 40 percent in the valleys and continued 60-80 percent in the mountains. Winds become west-northwest on Saturday afternoon with gusts to 20 to 30 mph during the afternoon behind the front. Forecast confidence beyond Sunday is low, but favors much cooler and unsettled early next week with a trough somewhere over the Pacific Northwest. Forecast models continue to struggle with current and recent tropical systems disrupting and enhancing the jet stream, particularly in the eastern Pacific near Cabo San Lucas and in the western Pacific Ocean. Temperatures cool 10-20 degrees on Saturday and another 5-10 degrees on Sunday.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None.
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DISCUSSION...JDS AVIATION.....NF SHORT TERM...KA LONG TERM....KA
NWS BOI Office Area Forecast Discussion