The first big winter storm of the season is now under formal warnings across Colorado's San Juan Mountains, and the two highways truckers fear most in the state are right in its path. The National Weather Service office in Grand Junction has the northwest and southwest San Juan Mountains under a winter storm warning through Monday, calling for 12 to 18 inches of snow above 10,000 feet with locally higher amounts and wind gusts to 45 mph. The NWS office in Pueblo has the eastern San Juans under a second warning from Sunday evening into Monday, with 8 to 14 inches expected over Wolf Creek Pass on US 160 and Cumbres Pass, and the storm's strongest wind — gusts to 50 mph, enough to build areas of blowing and drifting snow. Forecasters in both offices say travel could become very difficult to impossible, with the worst conditions Sunday night into the Monday morning commute.

Source: Autoblog, Nov. 1, 2026, reporting the NWS Grand Junction and NWS Pueblo warnings

The two warnings, in full

The Grand Junction warning was upgraded from a winter storm watch on Saturday morning and covers Telluride, Ouray, Silverton, Lake City, Rico and Hesperus, along with four high passes: Red Mountain, Molas, Coal Bank and Lizard Head. It runs from Sunday morning until noon Monday local time. The Pueblo warning covers the eastern San Juan Mountains above 10,000 feet from Sunday evening to Monday afternoon, and Pueblo expects the heaviest snow and the worst travel on Wolf Creek Pass and Cumbres Pass on Sunday night and Monday morning. Farther north, the Gore and Elk Mountains are under a winter weather advisory for 5 to 10 inches. A warning, in National Weather Service terms, means the conditions pose a threat to life or property and travel will become difficult to impossible — it is the office's most serious winter product short of a blizzard warning.

12–18 insnow expected above 10,000 feet in the northwest and southwest San Juan Mountains
8–14 inexpected over Wolf Creek Pass and Cumbres Pass in the eastern San Juans
50 mphstrongest forecast gusts, in the Pueblo warning area, with blowing and drifting snow
45 mphgusts in the Grand Junction warning area
10,000 ftelevation above which the heaviest snow falls — every named pass sits at or above it
Until Mondayboth warnings run past the Monday morning commute

Why Wolf Creek Pass worries truckers

Wolf Creek Pass carries US 160 over the eastern San Juans, and its west side is one of the most demanding descents in the American trucking network. According to the Colorado Department of Transportation, the road drops at a 7 percent grade for more than eight miles from the summit, with a hairpin curve six and a half miles down and two runaway truck ramps built into the descent. CDOT's guidance for truck drivers on this pass is specific: check the brakes before descending, hold a low speed in a low gear, and do not ride the brakes, which can overheat them. The summit's wide shoulder doubles as a chain-up area for traffic in both directions — on a warning night like Sunday, that shoulder is where trucks will be stopping to chain before the grade.

Red Mountain Pass: snow that is managed with explosives

On US 550, the Million Dollar Highway, Red Mountain Pass runs directly below avalanche terrain. CDOT installed remote avalanche control systems at slide paths on the pass in 2023 — two Gazex units and three O'Bellx units that use compressed air and gases to trigger controlled avalanches above the road while it is closed. Crews can run that work in the early morning, before commuter traffic builds, and CDOT says the systems shorten closures — but they still mean the highway can shut with little notice while control work is done. Across the state, CDOT and the Colorado Avalanche Information Center monitor 522 avalanche paths above state highways and Interstate 70, with active mitigation on 278 of them. Road conditions are published on COtrip and through 511.

For truckers crossing Colorado tonight

Check COtrip or 511 before rolling, not at the pass. Chain where the chain-up areas are — the Wolf Creek summit shoulder serves both directions — and remember CDOT's own rule for the descent: brakes checked first, low gear, low speed, never ride the brakes down the 7 percent grade. If avalanche control closes US 550 at Red Mountain, the closure is the control work itself; wait it out rather than routing onto unfamiliar mountain roads in the storm.

The same storm is flooding the valleys below the snow

The snow is only the top half of this storm. The system is riding an atmospheric river — the “Pineapple Express” pattern drawing moisture from near Hawaii — into ground already saturated by weeks of record autumn rain. Pagosa Springs, in the San Juan foothills, declared a local emergency after flash flooding last weekend and has been under river-crest warnings this weekend, and flood watches remain posted across the Southwest. Fox Weather, tracking the same system as it crosses the country, put the San Juan snow at 12 to 15 inches by Monday and quoted the NWS Pueblo office's Saturday warning to residents: “Folks, the window for flood preparations is closing.” The cross-country storm is expected to affect more than 35 states as it moves east through the week, toward the Interstate 95 corridor by Thursday and Friday.

Source: Fox Weather, cross-country storm coverage, Nov. 1, 2026

Beyond Colorado: Nevada's Ruby Mountains and four more states

Colorado holds the highest totals, but it is not alone on the alert map. The NWS office in Elko has a winter storm warning up for the Ruby Mountains and East Humboldt Range in northeast Nevada. Winter alerts of some level are also posted in Utah, Wyoming, Idaho and California, while flood watches stretch across Arizona, Nevada, Utah, New Mexico, Colorado and California — seven western states under snow or flood alerts in total this weekend, as Men's Journal's roundup of the National Weather Service products put it. For through-drivers, that means the storm is not a single-pass problem: the same weekend system is degrading routes across the whole interior West at once.

Source: Men's Journal, Oct. 31, 2026, rounding up the NWS alert map

What happens next

The worst travel in the San Juans is expected Sunday night into Monday morning, while both warnings are still in force and snow is falling on the Monday commute. The Grand Junction warning expires at noon Monday and the Pueblo warning on Monday afternoon; after that, forecasters expect the precipitation to taper even as valley flooding from rain and meltwater continues downstream into Tuesday. CDOT will post pass closures, chain restrictions and avalanche-control shutdowns on COtrip as they happen. Drivers with loads over Wolf Creek, Red Mountain, Molas, Coal Bank, Lizard Head or Cumbres passes should treat Sunday night as the deadline: cross before the storm peaks, or plan to wait it out below the passes.