Near-record warmth gives way to cooler, wetter weather and mountain snow. Idaho’s unusually mild November weather will continue through Friday, but a major pattern change will bring cooler temperatures, periods of valley rain, and accumulating snow to the mountains.
Afternoon temperatures will climb well into the 60s across many valleys Thursday and Friday. Boise could reach 70 degrees Thursday, putting the city within reach of the daily record. Twin Falls will also remain exceptionally mild, while temperatures in McCall reach the upper 50s.
The ridge responsible for the warmth will begin moving east Friday as a Pacific storm approaches the Northwest. That system will push a cold front through eastern Oregon Friday evening and western Idaho between midnight and 6 a.m. Saturday.
Forecast highs compared with daily records
| City | Thursday forecast | Thursday record | Friday forecast | Friday record |
|---|---|---|---|---|
| Boise | 70° | 70° | 69° | 70° |
| Twin Falls | 67° | 73° | 68° | 71° |
| McCall | 57° | 61° | 57° | 61° |
Boise has the best chance of tying a record Thursday. Friday’s forecast is also close, although increasing wind and clouds could keep temperatures just below record territory.
Southeast winds will increase Friday afternoon. Gusts could approach 30 mph along portions of the Snake River Plain, including the area between Boise and Twin Falls. The strongest winds are expected in Harney County, Oregon, where gusts could reach 45 mph.
Rain and mountain snow arrive Friday night
The first cold front will bring several hours of precipitation Friday night and Saturday morning. Valley locations can expect rain, with approximately 0.05 to 0.15 inches possible.
The Boise Mountains could receive around 0.35 inches of precipitation, while other mountain locations generally receive 0.10 to 0.25 inches.
Snow levels will initially be relatively high, so some ski-area base elevations could begin with rain or wet snow. The better accumulation will be near the summits and across the highest terrain.
Showers will gradually decrease Saturday as the system moves east. Boise’s high will fall from near 70 Friday to the middle 50s Saturday.
Brief break Sunday before the next system
Sunday should provide a short break between storms. Conditions will be mainly dry with temperatures recovering slightly, including a high near 60 in the Treasure Valley.
Another system will quickly approach from the Gulf of Alaska late Sunday. Precipitation could begin Sunday night and continue into Tuesday, with Monday currently appearing to have the greatest chance of rain and snow.
Snow levels will start near 6,000 feet Sunday night and lower to between 4,000 and 5,500 feet before precipitation ends. That should allow snow to reach most Idaho ski-area bases by Monday night or Tuesday.
Temperatures will continue trending downward, with Treasure Valley highs falling into the lower to middle 50s by Tuesday.
How much snow could Idaho ski areas receive?
These are early estimates for the Sunday night through Tuesday system. Exact amounts will depend on the storm’s track, precipitation intensity and how quickly snow levels fall.
| Idaho ski area | Estimated snow Sunday night through Tuesday | Outlook |
|---|---|---|
| Bogus Basin | 2-5 inches | Rain or wet snow could change to accumulating snow as colder air arrives |
| Tamarack Resort | 3-6 inches | Best accumulation expected on the upper mountain, with a later change to snow near the base |
| Brundage Mountain | 4-8 inches | One of the better-positioned resorts for accumulating snow from this pattern |
| Sun Valley Resort | 10-15 inches | Higher runs on Bald Mountain should receive more snow than the base |
| Soldier Mountain | 1-7 inches | Light accumulation possible, especially on the upper mountain |
| Pomerelle Mountain | 10-15 inches | Its higher base elevation should improve the chance of mainly snow |
| Magic Mountain | 6-10 inches | Appreciable accumulation possible, especially on the upper mountain |
Brundage Mountain and Tamarack Resort currently have the best potential for several inches of snow. Bogus Basin and Sun Valley could also pick up useful early-season accumulation, particularly on their upper slopes.
Pomerelle’s higher elevation gives it a better chance of seeing snow rather than rain. Soldier Mountain may receive lighter amounts unless the storm produces more precipitation than currently expected.
These totals remain preliminary. The next system is still several days away, and a slower or colder storm would increase snowfall. A faster and weaker system would produce lower totals.
Cooler and unsettled pattern may continue
The early-week system should move east by Tuesday, but the active weather pattern may not end there. Another Gulf of Alaska storm could approach the West Coast Wednesday, increasing the chance of additional precipitation late in the day.
The overall trend is clear: near-record warmth will continue through Friday, followed by a cooler and wetter pattern this weekend and next week. While the upcoming storms will not guarantee enough snow to open every resort, they should provide a more favorable setup for early-season snow accumulation and snowmaking.
Tonight
Partly cloudy, with a low around 40. Light southeast breeze around 6 mph after midnight.
Thursday
Sunny & continued unseasonably mild, with a high near 70. Light southeast breeze.
Thursday Night
Partly cloudy, with a low around 43. SE Wind 5-10.
Friday
Mostly sunny, breezy and unseasonably mild, with a high near 69. Southeast wind 10 to 15 mph, with gusts as high as 30 mph.
Friday Night
Showers, mainly after 1am. Low around 43. Southeast wind 10 to 15 mph becoming light south after midnight. Winds could gust as high as 26 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday
Showers likely, mainly before 2pm. Patchy fog before 9am. Otherwise, partly sunny, with a high near 56. Chance of precipitation is 60%.
Saturday Night
Partly cloudy, with a low around 37.
Sunday
Partly sunny, with a high near 61.
Sunday Night
A 20 percent chance of showers after 11pm. Mostly cloudy, with a low around 41.
Monday
A 40 percent chance of showers. Cloudy, with a high near 56.
Monday Night
Showers likely. Patchy fog. Otherwise, cloudy, with a low around 38. Chance of precipitation is 60%.
Tuesday
A 40 percent chance of showers. Patchy fog. Otherwise, mostly cloudy, with a high near 52.
Tuesday Night
A 20 percent chance of showers. Mostly cloudy, with a low around 34.
Wednesday
A 30 percent chance of showers. Patchy fog. Otherwise, mostly sunny, with a high near 54.
