Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average sea temperature in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
December's arrival comes with a mild decrease in the average high-temperature, moving subtly from a cool 51.3°F (10.7°C) in November to a chilly 44.4°F (6.9°C). A slight dip in temperature to an icy 37.6°F (3.1°C) marks the average nights during December.Humidity
The average relative humidity in December is 75%.Rainfall
In Chatham, in December, during 11.2 rainfall days, 2.05" (52mm) of precipitation is typically accumulated. Throughout the year, there are 142.4 rainfall days, and 22.09" (561mm) of precipitation is accumulated.Snowfall
January through April, November and December are months with snowfall. In December, it is snowing for 4.7 days. Throughout December, 0.67" (17mm) of snow is accumulated. Throughout the year, there are 20.8 snowfall days, and 4.37" (111mm) of snow is accumulated.Ocean temperature
In Chatham, in December, the average water temperature is 46°F (7.8°C).Note: In 46°F (7.8°C), even brief exposure to 55.4°F (13°C) feels biting, and anything less than 50°F (10°C) risks cold shock and impaired breathing, considering one's health.
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 6:47 am and sunset at 4:10 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 4:19 pm EST.
Sunshine
With an average of 4.3h of sunshine, December has the least sunshine of the year in Chatham.UV index
January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unsafe exposure to UV radiation for the average person.Note: In December, an average UV index of 2 transforms into the following instructions:
The majority are not significantly affected by prolonged sun exposure. Infants, children, and those with fair skin must always have protection. The Sun's radiation is especially intense around midday; try to stay in shade during this period. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Pay attention! The reflection of snow can enhance the Sun's UV radiation almost double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is it in December?
What is the average humidity in December in Chatham?
How many days does it rain in December?
How much does it snow in December?
What is the water temperature in December?
What is the month with the shortest days?
What is the average length of the day in December?
What time are sunrise and sunset in December?
What is the month with the least sunshine?
How many hours of sunshine does Chatham have in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Chatham, MA
- Average high temperature in December: 44.4°F
The warmest month (with the highest average high temperature) is August (71.6°F).
The months with the lowest average high temperature are January and February (39°F).
- Average low temperature in December: 37.6°F
The month with the highest average low temperature is August (68.2°F).
The coldest month (with the lowest average low temperature) is January (31.6°F).
Average pressure in December
Chatham, MA
- Average pressure in December: 30.02"Hg
The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in December
Chatham, MA
- Average wind speed in December: 17.5mph
The windiest month (with the highest average wind speed) is January (18mph).
The calmest month (with the lowest average wind speed) is August (11.4mph).
Average humidity in December
Chatham, MA
- Average humidity in December: 75%
The months with the highest relative humidity are June and July (85%).
The month with the lowest relative humidity is November (74%).
Average rainfall in December
Chatham, MA
- Average rainfall in December: 2.05"
The wettest month (with the highest rainfall) is October (2.83").
The driest month (with the least rainfall) is November (1.46").
Average rainfall days in December
Chatham, MA
- Average rainfall days in December: 11.2 days
The month with the highest number of rainy days is May (14.6 days).
The month with the least rainy days is February (8.3 days).
Average snowfall in December
Chatham, MA
- Average snowfall in December: 0.67"
The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Chatham, MA
- Average snowfall days in December: 4.7 days
The month with the highest number of snowfall days is January (6 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average sea temperature in December
Chatham, MA
- Average sea temperature in December: 46°F
The best month for swimming (with the highest average sea temperature) is August (67.6°F).
The coldest month (with the lowest average sea temperature) is March (39.8°F).
Average daylight in December /
Average sunshine in December
Chatham, MA
- Average daylight in December: 9h and 1min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 4h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 18min).
Average sunshine days in December
Chatham, MA
- Average sunshine days in December: 13.6 days
The month with the most sunshine days is August (17.6 days).
The month with the least sunshine days is January (13 days).
Average UV index in December
Chatham, MA
- Average UV index in December: 2
The months with the highest UV index are July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover in December
Chatham, MA
- Average cloud cover in December: 54
The month with the most cloud cover is December (Cloud cover 54).
The month with the least cloud cover is August (Cloud cover 27).
Average visibility in December
Chatham, MA
- 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).
Chatham, Massachusetts, USA
Weather forecast for your location
2. Allow the app to use your location