December weather forecastMerrimac, MA
December
Weather in December
The first month of the winter, December, is also a wintry month in Merrimac, Massachusetts, with an average temperature fluctuating between 37.9°F (3.3°C) and 27.7°F (-2.4°C).Temperature
December's onset brings a slight change in high-temperatures, falling from a frosty 48.2°F (9°C) in November to a cold 37.9°F (3.3°C). An average low-temperature of 27.7°F (-2.4°C) marks the nights throughout December.Humidity
In December, the average relative humidity is 77%.Rainfall
In Merrimac, in December, during 4.8 rainfall days, 0.51" (13mm) of precipitation is typically accumulated. Throughout the year, in Merrimac, there are 78.3 rainfall days, and 5.43" (138mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through May, November and December. The month with the most snowfall is December, when snow falls for 2.6 days and typically aggregates up to 0.71" (18mm) of snow.Daylight
With an average of 9h and 6min of daylight, December has the shortest days of the year.On the first day of the month, sunrise is at 6:55 am and sunset at 4:10 pm. On the last day of December, sunrise is at 7:14 am and sunset at 4:19 pm EST.
Sunshine
In December, the average sunshine is 4.9h.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 reading of 2, and below, represents a low health risk from exposure to the Sun's UV radiation for average individuals.Note: A daily maximum UV index of 2 in December translates into the following instructions:
Children, infants, and individuals with sensitive skin should be constantly protected from extended sun exposure. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly. Be careful! The Sun's UV radiation can nearly be doubled by the reflective quality of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Merrimac, MA
- Average high temperature in December: 37.9°F
The warmest month (with the highest average high temperature) is July (80.8°F).
The month with the lowest average high temperature is January (32.5°F).
- Average low temperature in December: 27.7°F
The month with the highest average low temperature is July (63°F).
The coldest month (with the lowest average low temperature) is January (20.5°F).
Average pressure in December
Merrimac, MA
- Average pressure in December: 30.03"Hg
The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Merrimac, MA
- Average wind speed in December: 8.9mph
The windiest month (with the highest average wind speed) is January (9.5mph).
The calmest months (with the lowest average wind speed) are July and August (5.7mph).
Average humidity in December
Merrimac, MA
- Average humidity in December: 77%
The month with the highest relative humidity is February (79%).
The month with the lowest relative humidity is April (71%).
Average rainfall in December
Merrimac, MA
- Average rainfall in December: 0.51"
The wettest month (with the highest rainfall) is November (0.67").
The driest month (with the least rainfall) is September (0.2").
Average rainfall days in December
Merrimac, MA
- Average rainfall days in December: 4.8 days
The month with the highest number of rainy days is July (8.8 days).
The month with the least rainy days is January (3.6 days).
Average snowfall in December
Merrimac, MA
- Average snowfall in December: 0.71"
The month with the highest snowfall is December (0.71").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in December
Merrimac, MA
- Average snowfall days in December: 2.6 days
The month with the highest number of snowfall days is February (5.3 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Merrimac, MA
- Average daylight in December: 9h and 6min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in December: 4h and 54min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in December
Merrimac, MA
- Average sunshine days in December: 23 days
The month with the most sunshine days is January (24.5 days).
The month with the least sunshine days is April (18.4 days).
Average UV index in December
Merrimac, MA
- 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, November and December (UV index 2).
Average cloud cover in December
Merrimac, MA
- Average cloud cover in December: 47
The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in December
Merrimac, 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).
