The cold, dry weather and freezing fog that has made roadways slick and dangerous in the morning will continue into the middle of next week in Whatcom County, the National Weather Service said.
Expect overnight lows near 30 and daytime highs of about 40, the weather service said.
Temperatures that low will cause freezing in places like Lake Padden. But its not cold enough to make the lake a solid surface to safely walk or play on.
An air stagnation advisory is in effect until noon Tuesday. The Northwest Clearn Air Agency has asked residents to refrain from using wood stoves or doing other burning until the advisory is lifted.
The weather service said a frontal system could arrive Tuesday night or Wednesday, returning rain to Western Washington and a chance of snow in higher elevations and Eastern Washington.
Snow levels will drop to between 3,500 and 4,000 feet by the middle of next week.
A strong high pressure system over the Northwest is expected to last through the weekend, maintaining stagnant air conditions that could cause breathing problems for vulnerable people.