Tuesday mornings cold, wet weather forced some school districts to open late or run buses on snow routes.
In Portland, schools west of the Willamette River were opening two hours late because of the icy conditions in the upper elevations. David Douglas school buses were on snow routes.
Schools in parts of Washington, Clackamas, Yamhill and Columbia counties also were opening two hours late because of the cold weather.
The National Weather Service predicts drizzle for most of the morning Tuesday, with temperatures reaching 40 degrees. Tuesday night, however, could see more freezing fog and icy conditions in higher elevations.
A high pressure system also is moving in, according to the weather service, which could bring sunshine and stagnant air.