The Weather Service has issued a winter weather advisory for the Kelso-Longview, Willamette Valley and Portland metro areas.
Sunday will have an 80 percent chance of rain and a high of 64, meteorologists said.
Ice accumulations of one-tenth of an inch are possible.
Many will wake to patchy freezing fog Friday morning for areas not still in the grip of the the Gorge winds. Below-normal temperatures are expected this weekend and into Monday across the entire northern half of the country, from the Pacific Northwest to ME and as far south as Oklahoma, Arkansas and Virginia, according to the Climate Prediction Center.
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The rain could stick around through Monday night and Tuesday, though chances diminish.
The rain could be heavy in some places, AccuWeather said.
Forecasters said no significant impacts were expected but were monitoring temperatures closely Sunday morning. "We expect a solid 1-3" rainfall across North Alabama and Southern Tennessee Saturday through Sunday morning, and as that rain ends some sleet and/or snow may mix with it for a brief period.