Winter Weather Advisory Covers Southern Idaho Mountains
Rain and mountain snow move across southern Idaho from Saturday evening through Sunday, with the advisory running until 5 p.m. Sunday.
Updated on Oct. 31, 2026 in Forecasts
The National Weather Service has issued a Winter Weather Advisory for southern Idaho from 6 p.m. Saturday through 5 p.m. Sunday as a storm system brings widespread rain, gusty winds, and mountain snow. Three to seven inches of snow is expected at Galena Summit in the Sun Valley Region and Big Lost Highlands above 7,000 feet.
Why it matters
An upper-level low moving inland from the Pacific coast is driving moisture across Idaho, with a heavy precipitation band arriving late Saturday night and lasting through Sunday night. Residents across the state face wet and windy conditions, along with snowfall in higher terrain.
The National Weather Service forecast calls for three to seven inches of snow at Galena Summit and 0.50 to 0.80 inches of rain on the Snake River Plain, with a 90% to 100% chance of at least 0.25 inches across the region. Forecasters have not resolved the Wednesday and Thursday pattern, which models split 60-40.
The players
National Weather Service
The National Weather Service is the federal agency responsible for issuing weather forecasts and advisories across the United States, including winter weather advisories for Idaho.
The details
Rain begins in the Central Mountains, Wood River Valley, and eastern Magic Valley after 6 p.m. Saturday and reaches the Snake River Plain mostly after 3 a.m. Sunday, with southeast winds gusting to 20 mph. Showers are expected to linger into Monday morning before conditions dry out from west to east as high pressure builds.
Timeline
Saturday, 6 p.m.: Organized rain begins in the Central Mountains and Wood River Valley.
Sunday, 3 a.m.: Rain showers reach the Snake River Plain.
Sunday, 5 p.m.: The Winter Weather Advisory expires.
Monday morning: Showers linger, then conditions begin drying out west to east.
Wednesday and Thursday: Forecast uncertainty remains due to a possible high-pressure ridge.
Seasonal Patterns
This advisory follows the National Weather Service's standard winter weather criteria, which trigger alerts for snow accumulation at elevations above 7,000 feet in southern Idaho. The storm's moisture arrives from a Pacific upper-level low, a pattern that frequently delivers mountain snow to the region in late fall.
Drivers on higher mountain routes, including passes above 7,000 feet, should expect snow-covered and slick conditions through Sunday evening. Residents on the Snake River Plain should plan for wet roads and southeast gusts up to 20 mph Sunday morning.
The takeaway
Wet and snowy conditions will be concentrated at higher elevations and along the Snake River Plain through Monday, so check road conditions before traveling in the mountains this weekend. Drying is expected to begin Monday morning, though the midweek forecast remains uncertain.
What happens next
Forecasters will reassess the Wednesday and Thursday pattern as high pressure builds after Monday's drying.
Further reading
For the latest outlooks, see Forecasts coverage for Idaho.
Source note: This article includes information reported by LocalNews8.
