After a week of record-breaking rainfall and temperatures running 10 to 20 degrees below normal, the Treasure Valley is in for a stunning stretch of early fall weather. Sunny skies, comfortable temperatures, and light winds will make Tuesday through Thursday some of the best outdoor days of the entire year.
How Does This Week's Weather Compare to Normal?
The upcoming stretch of weather will feel refreshingly comfortable after the recent extremes. Here is how the forecast highs compare to what is typical for this time of year:
| Date | Forecast High (Boise) | Normal High (Boise) | Forecast High (McCall) | Normal High (McCall) |
|---|---|---|---|---|
| Tuesday | 75°F | 84°F | 66°F | 74°F |
| Wednesday | 80°F | 83°F | 72°F | 74°F |
| Thursday | 84°F | 82°F | 74°F | 73°F |
| Friday | 76°F | 81°F | 67°F | 73°F |
| Saturday | 72°F | 80°F | 63°F | 72°F |
Tuesday will be the coolest day of the stretch, running about 9 degrees below normal for Boise, but the sunny skies and light winds will make it feel absolutely delightful. Wednesday and Thursday will be right at or slightly above normal, delivering what many consider the ideal early fall weather for the Treasure Valley. These are the kinds of days that make September one of the most beloved months in the Boise area.
Outdoor Activities: Make the Most of This Week
This stretch of weather is tailor-made for outdoor activities across the Treasure Valley and central Idaho. Here are some highlights:
Tuesday through Thursday will offer some of the best hiking, biking, and outdoor recreation conditions of the entire year. The Boise Foothills, Table Rock, and Camel's Back Park will be spectacular under sunny skies with temperatures in the mid-70s to low 80s. The recent rainfall has also settled the dust and greened up the landscape, making trails particularly enjoyable.
McCall and the central Idaho mountains will see comfortable temperatures in the low to mid-60s Tuesday and Wednesday, rising to near 70 degrees Thursday. The recent significant rainfall has dramatically improved conditions in the mountains, making this an excellent week for hiking, camping, and fall foliage viewing. The mountains received 1 to 1.5 inches of rainfall last week, and the combination of moisture and cooling temperatures will accelerate the fall color change.
Friday and Saturday will still be pleasant with highs in the low to mid-70s, though a cold front will bring gusty westerly winds and a slight cooldown. Outdoor activities are still very doable, but be prepared for breezy conditions.
Fire Season Update: Significant Improvement
Last week's rainfall event delivered the most significant moisture to the Treasure Valley and central Idaho since spring, and the impacts on the fire season have been dramatic. The central Idaho mountains received 1 to 1.5 inches of rainfall, dramatically reducing fire behavior and spread rates across active fire complexes. Fuel moisture levels have increased substantially after weeks of critically dry conditions following record summer heat.
Fire danger ratings across much of the region have dropped from critical to moderate or low levels, providing firefighters with a significant tactical advantage heading into the fall season. Air quality across the Treasure Valley has improved dramatically as rain washed smoke particles from the atmosphere. The combination of cooler temperatures, higher fuel moisture, and shorter days means the most dangerous period of the 2026 fire season is likely behind us.
End of September Outlook: Cooler and More Active Pattern
The longer-range forecast for the end of September suggests a continuation of the cooler and more active pattern that has developed over the past week. A large Pacific trough off the coast of British Columbia will bring a cold front with gusty westerly winds and a cooldown to normal or slightly below normal temperatures Friday through Saturday. A closed upper low is projected to steer inland over the area late Saturday through Sunday, bringing widespread precipitation to the northern half of the region.
Looking further ahead, the Climate Prediction Center's extended outlooks favor above-normal precipitation and below-normal temperatures for the Pacific Northwest through the end of September and into October. This pattern is consistent with an early transition to fall conditions, which would be welcome news for water supply and snowpack heading into the winter season. The active pattern also significantly reduces the risk of a late-season fire weather event.
Tonight
Clear, with a low around 48. Light wind.
Tuesday
Sunny& pleasant, with a high near 75. Light wind.
Tuesday Night
Mostly clear, with a low around 50. Light wind.
Wednesday
Sunny, warm and pleasant, with a high near 80. Light and variable wind.
Wednesday Night
Clear, with a low around 57. Light wind.
Thursday
Sunny & warmer, with a high near 84.
Thursday Night
Mostly clear, with a low around 58.
Friday
Sunny, with a high near 76.
Friday Night
Mostly clear, with a low around 54.
Saturday
Mostly sunny & cooler, with a high near 72.
Saturday Night
Partly cloudy, with a low around 51.
Sunday
Sunny, with a high near 68.
Sunday Night
Mostly clear, with a low around 49.
Monday
Sunny, with a high near 70.
