Forecasters say a mostly dry, high pressure system that has been sitting over the Northwest for a couple of weeks is causing dense fog in many parts of Washington.
The National Weather Service said visibility early Wednesday morning in the central Puget Sound area was a quarter-mile or less.
The high pressure has created a condition where the coast and mountains are sometimes more likely to see sunshine than lowlands and valleys.
Forecasters often forecast afternoon clearing in gloomy areas, but some days the clouds never lift.
Forecasters say Washington's foggy weather is likely to persist through the weekend with a change possible by Monday to colder weather and clearing, but still dry.