A Winter Storm Warning 2026 issued by the National Weather Service’s Weather Prediction Center is sending a striking midsummer alert across the western United States, with a powerful Pacific storm moving east bringing up to 36 inches of snow to the Sierra Nevada, Cascades, and northern Rockies even as July is just days away. The storm system, which began arriving Sunday June 28, is also triggering flooding concerns, mudslide risks, Flood Watches, and Lake Wind Advisories across Montana, with the alpine sections of Glacier National Park’s Going-to-the-Sun Road temporarily closing due to the conditions.
The Storm System: Where It’s Coming From
The mechanics behind a summer snowstorm are unusual but not unprecedented in the mountain west.
A sharply colder weather pattern is bringing mountain snow to parts of the northern Rockies, along with some record cold temperatures for the first full weekend of summer to parts of Idaho, Montana, and Wyoming, including some national parks during their busiest time of year. This colder pattern is due to a sharp southward plunge of the jet stream and accompanying cold air over the Northwest U.S. ABC7
This colder weather will first move into the Northwest and northern Rockies Friday, peak this weekend, and linger into Monday, perhaps Tuesday. ABC7
According to the Weather Prediction Center, snow is making its way to the Sierra Nevada and Cascades, including Washington, Oregon, and California. The early part of this storm runs from Sunday June 28 into Monday June 29, with increasing snow continuing through Sunday and lingering into Monday for the higher elevations of the Cascades, down into the Sierra, the Uinta, and the Northern U.S. Rockies. CBS News
Snow Totals: Up to 3 Feet at High Elevations
The snowfall amounts being forecast are significant even by mountain winter standards.
Weather experts are warning about a potentially heavy snowfall in the area this week, even as July starts. The greatest chance for accumulating snow is at elevations above 6,500 to 7,000-plus feet. CBS News
Snow is expected to fall at elevations as low as 6,000 feet in parts of western Montana and Idaho, and to 8,000 feet in northwest Wyoming. Several inches of accumulation are possible, especially on grassy areas. Ground temperatures on pavement and roads are quite warm from the recent heat. ABC7
In Montana, the warnings are highly specific and already active. A Winter Storm Warning is in effect until 9 AM Monday for the Butte and Blackfoot Region above 6,500 feet for 4 to 8 inches of snow, with 8 to 16 inches across the Anaconda Pintler Mountains. A separate Winter Storm Warning covers the Bitterroot and Sapphire Mountains above 6,500 feet for 4 to 8 inches, with up to 12 inches across the highest peaks. Northwest Beaverhead County faces 2 to 6 inches at pass level with more than a foot possible in higher terrain.
The Temperature Shock: Record Lows Possible
The temperature drop accompanying this storm is as dramatic as the snowfall totals.
Some of the coldest places in the northern Great Basin and northern Rockies could see nighttime lows plunge into the 30s this weekend into Monday or Tuesday. That could flirt with daily record lows in a few areas of eastern Oregon and Idaho, not to mention a summer frost or freeze in other higher elevation cold spots. ABC7
Even some larger cities of the interior Northwest and northern Great Basin will see morning lows dip into the 40s this weekend into Monday, including Boise, Reno, and parts of Utah’s Salt Lake Valley. Daytime highs in Seattle, Portland, Spokane, and Boise will be much cooler this weekend in either the 60s or at most low 70s after this week’s searing heat. But parts of the high country of Montana, northwest Wyoming, and Idaho may not see highs rise out of the 40s or 50s. ABC7
National Weather Service meteorologist Gigi Giralte told KQED the snow could come as a shock for people recreating or camping. “This is definitely more reminiscent of springtime weather. This is a little abnormal to see in late June.” CBS News
60 mph Winds and Fire Hazard in Nevada and Surrounding Valleys
The storm’s wind component is adding a dangerous secondary threat at lower elevations.
Southwest winds across eastern and southern Nevada and the surrounding valleys are expected to get gusts up to 60 mph on Sunday and into the week. That creates a fire hazard near lower ranges. CBS News
The National Weather Service also warns of snow on Sunday at the Ruby Mountains in northeastern Nevada, mainly in Elko County, as well as freezing temperatures and widespread frost after midnight. The chance of precipitation, including snow at higher elevations, is 50%. CBS News
In Montana, a Lake Wind Advisory is in effect until 3 AM Monday for the Flathead and Mission Valleys, with sustained south winds of 20 to 30 mph and gusts up to 35 mph expected at Flathead Lake. These winds and choppy conditions are dangerous for small craft.
Flooding and Mudslides: Montana’s Secondary Crisis
Beyond the snow, an entirely separate set of hazards is threatening communities in western Montana.
An unusually large area of precipitation will make its way south from Canada this afternoon through tomorrow, setting the stage for heavy mountain rainfall from the Glacier Region to the Mission Mountains. Swollen streams, isolated mudslides, and increased runoff are all possible. Campers and RVs parked close to streams or the Hungry Horse Reservoir should consider repositioning to higher ground today. The Washington Post
A Flood Watch is in effect through late Sunday night for the West Glacier Region, the Flathead and Mission Valleys, and the Potomac and Seeley Lake Region for the potential of flash flooding caused by excessive rainfall. Excessive runoff may result in flooding of creeks, streams, and other low-lying and flood-prone locations. High country mudslides are possible, especially near steep terrain, which could endanger hikers. The upper portions of the Going-to-the-Sun Road are vulnerable to rockfall or debris flow. The Washington Post
Winter Storm Warnings will continue to be in effect for the Bitterroot Mountains and areas across southwest Montana through tomorrow morning. Hypothermia risk and difficult travel will remain for folks looking to explore backcountry. The Washington Post
Going-to-the-Sun Road Temporarily Closes
The storm’s most visible immediate consequence hit one of the most famous mountain roads in North America.
The alpine sections of Going-to-the-Sun Road in Glacier National Park temporarily closed due to heavy rain and possible debris flow, a concerning development given that the road’s full length had only just opened for the summer season to vehicle traffic earlier in the week. The Washington Post
Roads over mountain pass summits could become slush or ice-covered, especially at night or early in the morning, including the Going-to-the-Sun Road in Glacier National Park. Visitors to Yellowstone, Grand Teton, and Glacier national parks are advised to dress for colder and wetter weather, including rain gear, sweatshirts, and long pants. Backcountry campers and hikers should dress for winter weather or consider delaying or canceling those plans. ABC7
Is June Snow in the Rockies Really Unusual?
The short answer is no, and the historical record makes that clear.
In the northern Rockies and Northwest high country, June snow is typical. June Mountain West snow has been recorded in multiple prior years including 2025, 2023, 2020, and 2019. Even July snow has been documented in 2016. Snow has fallen in June before in Denver, Flagstaff Arizona, Salt Lake City, and Tahoe City California. ABC7
June snow has been recorded around Lake Tahoe from 1910 to 2024. So, don’t be surprised if snow pops up in June or even July around Lake Tahoe. CBS News
What makes the 2026 event notable is not the snow itself but the combination of unusually high snowfall totals, a simultaneous flooding threat, 60 mph wind gusts, and the direct impact on high-traffic national parks at the peak of tourist season.
Latest Update: What to Expect Through Monday and Beyond
The Winter Storm Warning 2026 conditions are expected to persist into Monday before conditions begin to improve.
By Tuesday, winds will relax and the region will transition into a weak ridge of high pressure. Given the widespread precipitation, fog and low clouds could cause travel issues across Montana Tuesday morning. The lingering moisture will also support scattered showers later in the day. Near seasonable temperatures along with daily thunderstorm chances are possible through Friday. The Washington Post
Daytime highs will recover through the week, with Seattle, Portland, Spokane, and Boise returning to normal ranges once the cold front passes Tuesday. ABC7
For full ongoing coverage of warnings, watches, and advisories, follow Men’s Journal, The Weather Channel, and NBC Montana.
Broader Implications: Climate and Tourism in the Mountain West
The Winter Storm Warning 2026 arriving during the first full weekend of summer is a reminder of how rapidly and dramatically weather can swing in the mountain west, a region that experienced record heat just days before the storm’s arrival.
For the national parks most directly in the storm’s path, the timing is acutely difficult. Glacier National Park’s Going-to-the-Sun Road had only just reopened for the season. Yellowstone and Grand Teton are in the heart of their peak visitor period. The combination of snow, flooding risk, road closures, and mudslide danger creates a complex safety picture for the thousands of summer visitors already in the region.
The broader pattern, a sharp jet stream plunge bringing winter conditions to high-elevation areas during summer, is consistent with weather scientists’ observations about increasing volatility at mid-latitudes in recent decades.
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What Happens Next
The storm system is expected to clear by Tuesday, with winds relaxing and a weak ridge of high pressure building across Montana and the Northwest. Flood Watches and Winter Storm Warnings are set to expire Monday morning for most areas, though Winter Weather Advisories for the Absaroka and Beartooth Mountains remain in effect through Monday evening with wind gusts up to 55 mph possible. National park visitors should check park websites before traveling to affected areas, particularly for road status on the Going-to-the-Sun Road and Beartooth Highway.
FAQ
Where is the Winter Storm Warning 2026 in effect?
Active Winter Storm Warnings and Winter Weather Advisories cover portions of Montana, Idaho, Wyoming, Nevada, Oregon, California, and Washington state as of June 28, 2026. Montana’s specific warnings cover the Butte and Blackfoot Region, the Bitterroot and Sapphire Mountains, the Anaconda Pintler Mountains, and Northwest Beaverhead County, with snowfall totals ranging from 4 inches to over a foot at the highest elevations.
How much snow is the Winter Storm Warning 2026 forecast to bring?
The National Weather Service forecasts up to 36 inches of snow at the highest elevations of the Sierra Nevada and Cascades. In Montana, 4 to 16 inches are forecast across most warned areas, with up to 12 inches in the Bitterroot and Sapphire Mountains and potentially over a foot in the higher terrain of northwest Beaverhead County.
Is the Going-to-the-Sun Road in Glacier National Park closed due to the Winter Storm Warning 2026?
Yes. The alpine sections of Going-to-the-Sun Road temporarily closed due to heavy rain and the risk of debris flow on June 28, 2026. The closure is particularly notable because the road had only fully opened for the summer season earlier that same week. Visitors should check the Glacier National Park website for current road status before traveling.
Why is there a Winter Storm Warning in June 2026?
A sharp southward plunge of the jet stream brought an unusually deep cold air mass into the Pacific Northwest and northern Rockies during the first full weekend of summer 2026. While June snow in the northern Rockies is historically documented, with events recorded in 2025, 2023, 2020, and 2019, the combination of high snowfall totals, flooding risk, and 60 mph wind gusts makes the 2026 event more severe than typical June mountain weather.
Is there a flooding risk alongside the Winter Storm Warning 2026?
Yes. A Flood Watch is in effect for the West Glacier Region, Flathead and Mission Valleys, and the Potomac and Seeley Lake Region in Montana through late Sunday night. Swollen streams, isolated mudslides, and increased runoff threaten low-lying areas. Campers and RVs near streams or the Hungry Horse Reservoir have been advised to move to higher ground.
Sources and References
- Men’s Journal: https://www.mensjournal.com/news/winter-storm-warning-heavy-snow-up-to-3-feet-60-mph-winds-coming-this-week
- The Weather Channel: https://weather.com/2026/06/24/forecast/regional/june-snow-record-cold-forecast-northern-rockies-national-parks
- NBC Montana: https://nbcmontana.com/weather/forecasts/flooding-concerns-breezy-conditions-and-winter-storm-warnings-remain-in-effect
