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Arizona Winter Travel: Salted I-17 Can Still Turn Icy
Flagstaff, AZ – Arizona drivers preparing for Thanksgiving travel along Interstate 40 should know that even a freshly treated highway can remain dangerously icy. While much of the state is known for d
By Elliot Vaughn · 2026-11-11T19:35:55.731Z
Flagstaff, AZ – Arizona drivers preparing for Thanksgiving travel along Interstate 40 should know that even a freshly treated highway can remain dangerously icy. While much of the state is known for desert heat, northern Arizona's high elevations can bring freezing pavement, snowfall and hazardous road conditions that persist after maintenance crews have treated the roadway.
According to winter maintenance guidance from transportation agencies, conventional road salt becomes less effective as pavement temperatures approach 20 degrees Fahrenheit. Its ice melting ability declines further in the teens and single digits, although actual performance depends on the treatment used, moisture and pavement conditions.
Why Treated Arizona Highways Can Still Freeze Road salt lowers water's freezing point, helping melt snow and ice. Other winter treatments can reduce ice buildup, but none guarantees safe traction.
Around 20 degrees, conventional salt works more slowly than it does near freezing. Below approximately 15 degrees, salt alone may struggle to melt ice quickly enough to improve driving conditions.
That matters along I 40 through Kingman in Mohave County, Williams and Flagstaff in Coconino County, and Winslow in Navajo County.
Other major routes, including I 17 between Phoenix and Flagstaff, can also become hazardous as drivers climb into colder mountain terrain.
Bridges, overpasses, shaded curves and higher elevation stretches deserve particular attention because ice can persist even after nearby pavement begins to clear.
Thanksgiving Travel Could Increase the Danger Thanksgiving falls Thursday, Nov. 26, bringing holiday travelers onto Arizona highways connecting Phoenix, Flagstaff, northern Arizona communities and neighboring states.
If snow, freezing precipitation or rapidly falling temperatures develop during the holiday travel period, treated roads could remain dangerously slick.
The elevation difference is significant. Phoenix sits near 1,100 feet above sea level, while Flagstaff is approximately 7,000 feet. Drivers can encounter dramatically different temperatures during the same trip.
The Arizona Department of Transportation uses snowplows and winter maintenance treatments, but no method guarantees ice free pavement under every condition.
Before departing, motorists should check National Weather Service forecasts and AZ511 for updated highway conditions, closures, traffic cameras and travel alerts.
The bottom line: Treated does not mean safe. Reduce speed, increase following distances and remain alert for icy patches, particularly on mountain routes and during overnight travel.