Boise, ID – Warmer weekend weather across Idaho will give way to a sharp cooldown and widespread rain as a frontal system moves into the region early this week.
According to the National Weather Service in Boise, showers will increase late Sunday night into Monday, September 29, with the highest chance of precipitation occurring Monday across southern Idaho and eastern Oregon. Forecast models show rain probabilities peaking at 70% to 80% in cities including Boise, Nampa, Caldwell, and Twin Falls.
Daytime highs, which reached the mid-80s in parts of the Treasure Valley this weekend, are expected to fall by nearly 20 degrees by Tuesday. Boise will cool from 84°F on Sunday to highs in the upper 60s by midweek. McCall, which topped out at 76°F Sunday, will dip to the 50s by Wednesday.
Rain chances will persist through Thursday, October 2, though coverage will gradually taper off as the week progresses. Temperatures will stay in a much cooler range, with overnight lows in the 30s and 40s across much of the region.
Drivers should anticipate wet roads and potential travel slowdowns Monday and Tuesday, especially during the morning commute. The weather service advises planning for extra time and being prepared for rapidly changing conditions.
