Saturday, Dec. 20 – Sunny but sharply colder with persistent gusty winds 

A high-impact weather day. Periods of rain overspread the area before dawn and continue through the morning, occasionally heavy, especially early. Strong south winds gust 40–45 mph before shifting west during the afternoon as a powerful cold front moves through. Rain tapers by mid to late afternoon, followed by rapidly falling temperatures, clearing skies, and blustery west winds Friday night. 
 ● High: 56 to 58°F (early) | Low: 25 to 27°F | Wind: South 15 to 20 mph with gusts 40–45 mph; shifting west and remaining gusty overnight  ● Sky: Cloudy with rain early, clearing late  ● Chance of precipitation: 100 percent

A quiet and seasonably mild December day with light winds and abundant sunshine early, followed by increasing high clouds late in the day as a strong storm system approaches from the west. Conditions remain dry through the evening, but rain spreads into Waltham after midnight as winds begin to increase from the south overnight. 
● High: 48 to 50°F | Low: 38 to 40°F | Wind: Calm becoming south 5 to 10 mph overnight, gusts up to 30 mph late ● Sky: Mostly sunny early, becoming cloudy overnight ● Chance of precipitation: 80 percent late night

Mostly sunny with highs near 30. Dry conditions persist as the cold pattern continues.
● High: Near 30°F | Low: Upper teens ● Chance of precipitation: 0 percent