Upcoming Weather Forecast for Snohomish County – Dec 4 to Dec 10Sunday (Dec 4): A slight chance of rain and snow after 2pm. Tuesday ( Dec 6): A chance of rain and snow before 11am, then a chance of rain. Thursday Night : Rain likely before 2am, then rain and snow likely. Mostly cloudy, with a low around 33.: Rain likely before 2am, then rain and snow likely. Rain and snow likely.