Mercer Island Week Ahead Forecast: Dangerous Driving Conditions

MERCER ISLAND, WA - What is fog and why has it been happening so much lately? Fog is essentially just a cloud at ground level. Fog forms when the air temperature and the dew point (the temperature where water vapor becomes suspended in the air) are within 4 degrees of each other, and those conditions have persisted recently.

Of course, fog is not dangerous on its own. But combine fog with early-winter darkness, unpredictable drivers, and freezing temperatures ... you've got a recipe for dangerous driving conditions. We're going to see fog every morning this week, so please be careful.

Here's the Puget Sound week-ahead forecast from the National Weather Service:

Monday: Patchy fog before 10am. Otherwise, sunny, with a high near 46. South wind around 5 mph.

Monday Night: Areas of fog after 4am. Otherwise, partly cloudy, with a low around 37. South southeast wind 3 to 7 mph.

Tuesday: Areas of fog before 10am. Otherwise, mostly sunny, with a high near 48. Light south wind.

Tuesday Night: Areas of fog after 10pm. Otherwise, partly cloudy, with a low around 38.

Wednesday: Areas of fog before 10am. Otherwise, mostly sunny, with a high near 48.

Wednesday Night: Partly cloudy, with a low around 39.

Thursday: Partly sunny, with a high near 48.

Thursday Night: A chance of rain. Mostly cloudy, with a low around 40.

Friday: A chance of rain. Mostly cloudy, with a high near 47.

Friday Night: A chance of rain. Mostly cloudy, with a low around 43

Image by Julio Cortez/Associated Press