December weather forecastMystic, CT
December
Weather in December
The arrival of December witnesses Mystic embracing winter once again, with temperatures dropping to an average high of 42.3°F (5.7°C). The city prepares for the holiday season, with festive decor adding to its charm. Snow starts to reappear, dusting the cityscape with a light coat and bringing around 4.5 snowfall days. Despite the cold, the holiday events and festive spirit keep the city vibrant and bustling with activity. Mystic in December, with its snow-covered streets, decorated marinas, and twinkling lights, transforms into a lively winter wonderland.Temperature
The arrival of December signals a subtle shift in temperature, down from a fresh 51.3°F (10.7°C) in November to an icy 42.3°F (5.7°C). Mystic, during the December nights, maintains an average temperature of 33.4°F (0.8°C), closely aligned with its daytime readings.Humidity
In December, the average relative humidity is 75%.Rainfall
The month with the most rainfall is December, when the rain falls for 13.4 days and typically aggregates up to 3.86" (98mm) of precipitation.Snowfall
January through April, October through December are months with snowfall. In Mystic, during December, snow falls for 4.5 days and regularly aggregates up to 1.18" (30mm) of snow. Throughout the year, there are 24.7 snowfall days, and 7.87" (200mm) of snow is accumulated.Ocean temperature
In Mystic, in December, the average water temperature is 48.6°F (9.2°C).Note: Unprotected swimming in 48.6°F (9.2°C) is dangerous due to potential cold shock. Especially when temperatures go below 50°F (10°C), leading to hyperventilation.
Daylight
With an average of 9h and 12min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 6:55 am and sunset at 4:19 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 4:28 pm EST.
Sunshine
The months with the least sunshine in Mystic are February and December, with an average of 4.9h of sunshine.UV index
The months with the lowest UV index are January through March and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health hazard from exposure to the Sun's UV rays for average individuals.Note: In December, a regular UV index of 2 translates into these guidelines:
While most individuals can withstand prolonged sun exposure, it is imperative that babies, children, and those with sensitive skin always be shielded. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. During bright days, sunglasses that offer UVA and UVB defense are recommended. Consider this! The reflection from snow can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Mystic, CT
- Average high temperature in December: 42.3°F
The warmest month (with the highest average high temperature) is July (77.9°F).
The month with the lowest average high temperature is January (36.5°F).
- Average low temperature in December: 33.4°F
The month with the highest average low temperature is July (66.9°F).
The coldest month (with the lowest average low temperature) is January (26.6°F).
Average pressure in December
Mystic, CT
- Average pressure in December: 30.04"Hg
The month with the highest atmospheric pressure is November (30.08"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in December
Mystic, CT
- Average wind speed in December: 11.9mph
The windiest month (with the highest average wind speed) is January (12.4mph).
The calmest month (with the lowest average wind speed) is August (8.1mph).
Average humidity in December
Mystic, CT
- Average humidity in December: 75%
The month with the highest relative humidity is June (81%).
The months with the lowest relative humidity are January, March, April and November (74%).
Average rainfall in December
Mystic, CT
- Average rainfall in December: 3.86"
The wettest month (with the highest rainfall) is December (3.86").
The driest month (with the least rainfall) is September (1.73").
Average rainfall days in December
Mystic, CT
- Average rainfall days in December: 13.4 days
The month with the highest number of rainy days is July (17.1 days).
The month with the least rainy days is February (10.1 days).
Average snowfall in December
Mystic, CT
- Average snowfall in December: 1.18"
The month with the highest snowfall is March (2.44").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Mystic, CT
- Average snowfall days in December: 4.5 days
The month with the highest number of snowfall days is January (6.8 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average sea temperature in December
Mystic, CT
- Average sea temperature in December: 48.6°F
The best month for swimming (with the highest average sea temperature) is August (70.3°F).
The coldest month (with the lowest average sea temperature) is February (37.9°F).
Average daylight in December /
Average sunshine in December
Mystic, CT
- Average daylight in December: 9h and 12min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 4h and 54min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The months with the least sunshine are February and December (Average sunshine: 4h and 54min).
Average sunshine days in December
Mystic, CT
- Average sunshine days in December: 14.2 days
The month with the most sunshine days is November (16.5 days).
The months with the least sunshine days are June and July (11.7 days).
Average UV index in December
Mystic, CT
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March and December (UV index 2).
Average cloud cover in December
Mystic, CT
- Average cloud cover in December: 47
The months with the most cloud cover are February, March and December (Cloud cover 47).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in December
Mystic, CT
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
