Summer's final gasp arrives Friday, but a powerful cold front will bring a dramatic taste of fall to the Treasure Valley this weekend in Scott Dorval's video forecast
After another warm day Friday with highs climbing to around 86 degrees, temperatures will tumble behind a strong cold front moving through Friday night and Saturday morning. By Saturday afternoon, highs are expected to reach only the lower 60s, a drop of roughly 24 degrees in just one day.
The cooler trend continues into Sunday and Columbus Day, when highs may struggle to get out of the upper 50s. That's nearly 30 degrees cooler than Friday's warmth.
Sharpest Cooldown of the Season
Saturday's highs will end up 20 to 30 degrees cooler than Friday across southwest Idaho. The cooldown is expected to be accompanied by gusty northwest winds and increasing cloud cover.
Here's how temperatures compare to Friday's expected high:
- Saturday: 24° colder
- Sunday: 28° colder
- Columbus Day: 29° colder
- Tuesday: 23° colder
- Wednesday: 23° colder
- Thursday: 22° colder
While temperatures recover slightly next week, they remain well below Friday's summer-like levels.
Rain Chances Increase
Moisture associated with the remnants of former Hurricane Rachel may become involved in the weather pattern Sunday into Monday. The heaviest rainfall potential currently appears to be across south-central Idaho, though some showers are expected across much of southwest Idaho.
For Boise, rainfall amounts currently look light, but forecast confidence remains lower regarding exactly how far west the tropical moisture plume extends.
Mountain Snow Returns
The incoming storm system will also bring a return of mountain snow. Snow levels are expected to remain relatively high, generally between 7,000 and 9,000 feet, but some of the highest peaks could pick up light accumulations through early next week.
Frost and Freeze Concerns
The cold air will also create the first widespread frost and freeze concerns of the season.
The National Weather Service indicates frost and freeze conditions are possible Sunday morning in colder locations, becoming more widespread Monday morning as overnight temperatures drop into the 30s.
Looking Ahead
The unsettled pattern lingers through much of next week with occasional shower chances and temperatures remaining below normal. Highs are expected to rebound into the lower 60s by Tuesday through Thursday, but the Treasure Valley will remain firmly in fall mode after Friday's brief return to summer.
Bottom line: Enjoy Friday's 86-degree warmth while it lasts. By Sunday and Monday, Boise will be nearly 30 degrees cooler with clouds, showers, and much more autumn-like weather settling across the region.
Tonight
Clear, with a low around 53. Calm wind becoming southeast around 5 mph.
Friday
Sunny, with a high near 86. Light and variable wind becoming north northwest 5 to 7 mph in the afternoon.
Friday Night
Mostly cloudy, with a low around 47. West northwest wind 3 to 6 mph.
Saturday
Partly sunny, with a high near 62. Calm wind becoming northwest 5 to 8 mph in the afternoon. Winds could gust as high as 20 mph.
Saturday Night
A 20 percent chance of showers before 4am. Mostly cloudy, with a low around 40. West wind 5 to 9 mph, with gusts as high as 20 mph.
Sunday
A 20 percent chance of showers after 9am. Partly sunny, with a high near 58.
Sunday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 37.
Columbus Day
A 30 percent chance of showers. Partly sunny, with a high near 57.
Monday Night
A 30 percent chance of showers, mainly before midnight. Patchy fog after 2am. Otherwise, partly cloudy, with a low around 39.
Tuesday
Areas of fog before 10am. Otherwise, mostly sunny, with a high near 63.
Tuesday Night
A 20 percent chance of showers. Partly cloudy, with a low around 42.
Wednesday
A 20 percent chance of showers. Patchy fog. Otherwise, mostly sunny, with a high near 63.
Wednesday Night
Mostly clear, with a low around 39.
Thursday
Patchy fog. Otherwise, sunny, with a high near 64.
