Heavy snowfall has closed Highway 20, the North Cascades Highway, in both directions at milepost No. 134, about 10 miles east of the mountain village of Diablo.
Harmony Haveman-Weinberg, with the state Department of Transportation in Shoreline, said it was unknown how long the road would be closed or whether this closure would last through the season.
State officials are evaluating the situation, Haveman said.
Rockslides, heavy snow or the threat of avalanches generally close the pass for several months from late fall through early spring. The pass connects Western Washington with the Methow Valley cities of Winthrop and Twisp.