Waltham Weather Outlook: Dec. 10 to Dec. 17, 2025 

A mild, cloudy start to the period gives way to a sweeping cold front tonight, bringing a quick round of rain followed by sharply colder and much windier weather Thursday into Friday. Wind chills fall into the single digits Thursday night as arctic air settles in. The weekend stays cold, with Saturday generally dry; the risk for accumulating snow Saturday night into Sunday has decreased but remains uncertain and could shift with future model trends. Another push of arctic air arrives late Sunday into early next week with temperatures staying well below normal and mainly dry conditions dominating.