Boise, ID – The National Weather Service in Boise reports that a new stretch of wet weather will move across southwestern Idaho and eastern Oregon through midweek, bringing steady rain to lower elevations and a shifting rain–snow mix to the mountains as temperatures rise above normal.
The agency notes that rapidly increasing snow levels will keep most of the Treasure Valley under consistent rainfall, while higher elevations such as Bogus Basin, Banner Summit, and Brundage Mountain experience changing precipitation types through Wednesday.
Warm Conditions Drive Rain in the Valley
Forecasters explain that temperatures will remain several degrees above seasonal averages, allowing rain to dominate across lower elevations. Highs are expected to range from the mid-40s to near 60°F across southern Idaho, with overnight lows holding in the upper 20s to 40s.
The NWS highlights that the most active period arrives from Monday night through Wednesday, when valley rain chances climb to 50–70%. Mountain areas, where moisture will be more persistent, could see precipitation probabilities between 80–100%.
Mountain Passes to See Mixed Precipitation
Higher terrain will deal with fluctuating temperatures, leading to periods of both rain and snow throughout the first half of the week. The NWS states, “Snow levels will rise quickly, limiting accumulating snow at many mid-elevation zones but maintaining a rain–snow mix across upper slopes and passes.”
Travelers heading into the mountains should prepare for variable road conditions, as precipitation type may shift repeatedly through Wednesday. Slick surfaces are possible where temperatures briefly dip near freezing, especially overnight.
Streams Could Rise With Snowmelt
Snowmelt driven by warm temperatures and continuous precipitation may cause small rises in area creeks and streams. While the NWS emphasizes that widespread flooding is not expected, residents near waterways should remain aware of changing conditions.
Local hydrologists point out that extended periods of rainfall can still lead to rapid water level changes in narrow channels. Monitoring forecasts becomes increasingly important when mixed precipitation interacts with existing mountain snowpack.
Cooler Air Returns Late Week
By late Thursday, a modest cooldown is expected to shift much of the mountain precipitation back to mostly snow. Lower elevations will continue to see occasional rain showers but with lighter intensity compared to the midweek stretch.
Forecasters say this pattern change will temporarily ease melting concerns and may improve consistency for mountain snowpack heading into the weekend.
What Residents Should Know
The upcoming weather system is typical for early-season transitions when warm, moist air overrides existing snowpack. Southwest Idaho’s valleys can expect wet commutes, while mountain travelers should anticipate rapidly changing conditions.
Boise residents are encouraged to check daily NWS updates for evolving details and be mindful of potential impacts to recreation areas, mountain roads, and localized streams.
Share Your Experience
Have you seen impacts from the shifting rain and snow in your area? Share your observations in the comments below.
