Residents of western Washington can expect dense morning fog at the start of the week, especially during the morning commute. The National Weather Service warned that visibility could drop below half a mile in some areas, so drivers are advised to slow down and take extra care on the road. Conditions like these are typical for this time of year: long autumn nights cool the air more significantly, creating low clouds and fog.
By noon Monday, the fog will lift, giving way to clear skies, sunshine and temperatures around 65–66°F—slightly above the seasonal average of 64°F. A similar pattern will continue over the next several days, with foggy mornings transitioning to calm, sunny weather. Thursday will be the warmest day, with temperatures reaching about 70°F. On Friday, however, the weather pattern is expected to change noticeably as scattered showers move into the region and may continue through the weekend, though the exact amount of rainfall remains uncertain.
Based on: Seattle weather: Foggy start to week of ‘benign’ weather