While Arizona and Nevada brace for 50 mph fire winds and 4 percent humidity this weekend, the Idaho-Montana border country is heading in the exact opposite direction.
Winter Storm Watch in effect from Saturday evening through Monday morning above 6,500 feet across Lemhi County, Idaho and the Bitterroot and Sapphire ranges of Montana. Up to 8 inches of heavy wet snow is possible in some areas.
The Watch: Where, When and How Much
The National Weather Service in Missoula issued Winter Storm Watches Thursday for four zones in Idaho and Montana, all in effect from Saturday evening through Monday morning:
In Idaho: Eastern and Western Lemhi County, including Highway 28 from Tendoy to Lone Pine, Lemhi Pass, Bannock Pass and the Williams Creek Summit area — all above 6,500 feet.
In Montana: The Bitterroot and Sapphire Mountains — up to 8 inches of wet snow possible — and the Butte/Blackfoot Region including Georgetown Lake and the Anaconda and Pintler Mountains, where 6 or more inches are possible.
“Cold temperatures and wet snow will elevate the risk of hypothermia,” the Missoula office warned, adding that heavy wet snow may down trees across backcountry roadways, blocking access for potentially days.
Why Late June Snow Happens Here
Lemhi County sits in one of the most rugged and least-visited corners of the American West — a sprawling high-elevation county in central Idaho where the Lemhi Range and the Continental Divide top 10,000 to 11,000 feet. At 6,500 feet — the watch threshold — June snow is uncommon but not unprecedented.
Lemhi Pass, specifically named in the watch, is the same Continental Divide crossing used by Lewis and Clark in 1805 — one of the most historically significant backcountry routes in the American West. At 7,373 feet, it sits well above the watch threshold.
The same cold front driving critical fire weather across the Southwest this weekend is pushing a late-season trough of moisture into the Northern Rockies, where higher terrain intercepts it as snow rather than rain.
What This Means for Weekend Backcountry Plans
This watch arrives at peak late June backcountry season. Lemhi County and the Bitterroot Wilderness are among the most popular early-summer backpacking and overlanding destinations in Idaho and Montana — and a surprise 6 to 8 inch snowfall at route elevation can close passes, strand vehicles, add dangerous weight to tents and lead to hypothermia in seconds with wet clothing.
The NWS Missoula office is direct: “Persons should consider delaying travel across high elevation backcountry roadways.” The office recommends a winter storm kit in any vehicle heading into the backcountry this weekend — tire chains, booster cables, flashlight, shovel, blankets, extra clothing, water and a first aid kit. If you become stranded in wet snow, your vehicle is your shelter. Do not leave it.
Anyone with plans on Highway 28 between Tendoy and Lone Pine, the Lemhi Pass road or the Williams Creek Summit route should check 511.idaho.gov for road conditions before departing and monitor the latest from weather.gov/mso. The watch may upgrade to a Winter Storm Warning before Saturday.
