A heavy, predawn snowstorm is causing problems for drivers on Whidbey Island.

Snow was accumulating on Highway 525 and Highway 20 just after 6:30 a.m. Tuesday, with the worst-hit areas near Milepost 21 on Highway 525 about a mile south of Classic Road, and on Highway 20 near the Navy’s Outlying Field.

Traffic was at a crawl just north of Freeland and also near Rhododendren Park, where traffic was slowing due to a driver in the ditch just before 7 a.m.

Traffic on the highway was slowing to 30 mph in places.

A state Department of Transportation snowplow was trying to keep Highway 525 clear north of Freeland. When the snowplow driver pulled over near Ledgewood to allow a line of cars to pass, the first driver behind the plow promptly loss control and went off the roadway.

The heaviest snowfall before 7 a.m. was in Maxwelton Valley, where near-whiteout conditions were observed near the fire station on French Road, and on Central Whidbey, just south of Coupeville. Approximately 2 inches of fresh snow had fallen early Tuesday morning.

South Whidbey School District officials have canceled school for Tuesday.