Unseasonably Warm and Dry Pattern Holds Through Friday
Upper-level high pressure continues to dominate Southwest Idaho, maintaining very warm and dry conditions through the rest of the workweek. Daily high temperatures in Boise will remain near record-setting territory—hovering in the mid-to-upper 80s, roughly 15 to 20 degrees above seasonal norms.
Abundant sunshine, calm winds, and clear night skies will lead to efficient radiational cooling, dropping overnight lows into the upper 40s to mid-50s across the lower valleys, with mountain valleys dipping into the 30s.
Big temperatures drop still on schedule for the weekend in Scott Dorval's video forecast
Weekend Cold Front Drops Temps 20 Degrees; Showers Possible Early Next Week
A major seasonal pattern change arrives this weekend as a strong upper-level trough moves south from British Columbia. High-elevation winds will begin ramping up Friday, with a sharp cold front pushing through the region on Saturday. The front will bring breezy valley winds and plummeting temperatures—dropping Saturday’s highs by about 20 degrees compared to Friday.
By Sunday into early next week, the trough is expected to close off and settle into Southeast Oregon and Southwest Idaho. Ensemble models indicate the potential for significant rainfall to develop east of the low center where deeper moisture will gather:
- Precipitation Chances: Central Idaho mountains hold a 40–60% chance of rain and high-peak snow Saturday night through Tuesday, while the Treasure Valley and surrounding lower elevations sit at a 10–30% chance of showers.
- Colder Air & Snow Levels: High temperatures will settle 5 to 10 degrees below normal Sunday through Tuesday, pushing mountain locations below freezing at night. Depending on the exact track of the low, snow levels could drop near 4,000 feet in parts of SE Oregon, with patchy morning fog and possible low-elevation frost potential as skies clear.
Boise Daily Forecast Highs vs. Historic Records (Today – Friday)
| Day | Forecast High (°F) | Historic Record High (°F) | Year Record Set |
| Tuesday (Oct 6) | 86° | 87° | 1988 |
| Wednesday (Oct 7) | 86° | 86° | 1980 |
| Thursday (Oct 8) | 86° | 88° | 1910 |
| Friday (Oct 9) | 88° | 90° | 2015 |
Tonight
Clear, with a low around 51. Light wind.
Wednesday
Sunny, with a high near 86. Light wind.
Wednesday Night
Clear, with a low around 52. Light wind.
Thursday
Sunny, with a high near 86. Light and variable wind.
Thursday Night
Clear, with a low around 55. Light and variable wind.
Friday
Sunny, with a high near 88.
Friday Night
Partly cloudy, with a low around 48.
Saturday
Mostly sunny, breezy & much cooler with a high near 64.
Saturday Night
A 40 percent chance of showers. Mostly cloudy & colder, with a low around 40.
Sunday
A 20 percent chance of showers after noon. Partly sunny, breezy & quite cool, with a high near 59.
Sunday Night
A 30 percent chance of showers. Patchy fog. Otherwise, partly cloudy & cold, with a low around 39.
Columbus Day
A 20 percent chance of showers. Patchy fog. Otherwise, mostly sunny, with a high near 58.
Monday Night
A 30 percent chance of showers. Partly cloudy, with a low around 40.
Tuesday
A 20 percent chance of showers. Patchy fog. Otherwise, mostly sunny, with a high near 61.
