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
The advent of December brings a slight shift in average high-temperature, moving from a cool 50.9°F (10.5°C) in November to a cold 42.4°F (5.8°C). In Onset, the nocturnal temperatures throughout December show a marginal dip from the daytime averages, settling at a still icy 34.2°F (1.2°C).Humidity
In December, the average relative humidity is 76%.Rainfall
December is the month with the most rainfall. Rain falls for 12.5 days and accumulates 3.58" (91mm) of precipitation.Snowfall
January through April, October through December are months with snowfall. In December, it is snowing for 3.5 days. Throughout December, 1.26" (32mm) of snow is accumulated. Throughout the year, there are 21.7 snowfall days, and 8.43" (214mm) of snow is accumulated.Ocean temperature
In Onset, in December, the average water temperature is 46.9°F (8.3°C).Note: To swim in 46.9°F (8.3°C) at less than 50°F (10°C), ensure you're well-protected. Without it, be prepared for a sudden jolt of cold and breathing issues. Remember, even 55.4°F (13°C) is not welcoming.
Daylight
December has the shortest days of the year, with an average of 9h and 12min of daylight.On the first day of the month, sunrise is at 6:50 am and sunset at 4:12 pm. On the last day of December, sunrise is at 7:09 am and sunset at 4:22 pm EST.
Sunshine
The months with the least sunshine in Onset are February and December, with an average of 4.8h of sunshine.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 of 2, and less, symbolizes a low health risk from exposure to the Sun's UV radiation for the ordinary person.Note: The maximum daily UV index of 2 during December translates into the following directions:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is December cold?
What is the average humidity in December?
What is the wettest month?
How much does it rain in December?
How many days does it snow in December?
What is the ocean temperature in December?
What is the month with the shortest days?
What is the average length of the day in December?
When are sunrise and sunset in December?
What is the month with the least sunshine?
How long on average sun shines in December?
What is the month with the lowest UV index in Onset?
What is the UV index reading in December?
Average temperature in December
Onset, MA
- Average high temperature in December: 42.4°F
The warmest month (with the highest average high temperature) is July (75.6°F).
The month with the lowest average high temperature is January (36.9°F).
- Average low temperature in December: 34.2°F
The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is January (27.7°F).
Average pressure in December
Onset, 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 (29.93"Hg).
Average wind speed in December
Onset, MA
- Average wind speed in December: 13mph
The windiest month (with the highest average wind speed) is January (13.7mph).
The calmest month (with the lowest average wind speed) is August (8.7mph).
Average humidity in December
Onset, MA
- Average humidity in December: 76%
The months with the highest relative humidity are June and July (81%).
The months with the lowest relative humidity are March and November (74%).
Average rainfall in December
Onset, MA
- Average rainfall in December: 3.58"
The wettest month (with the highest rainfall) is December (3.58").
The driest month (with the least rainfall) is September (1.81").
Average rainfall days in December
Onset, MA
- Average rainfall days in December: 12.5 days
The month with the highest number of rainy days is July (16 days).
The month with the least rainy days is January (9 days).
Average snowfall in December
Onset, MA
- Average snowfall in December: 1.26"
The months with the highest snowfall are February and March (2.28").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Onset, MA
- Average snowfall days in December: 3.5 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 and September (0 days).
Average sea temperature in December
Onset, MA
- Average sea temperature in December: 46.9°F
The best month for swimming (with the highest average sea temperature) is August (68.4°F).
The coldest month (with the lowest average sea temperature) is February (38.2°F).
Average daylight in December /
Average sunshine in December
Onset, 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 5min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are February and December (Average sunshine: 4h and 48min).
Average sunshine days in December
Onset, MA
- Average sunshine days in December: 15.6 days
The month with the most sunshine days is November (16.3 days).
The month with the least sunshine days is April (12.5 days).
Average UV index in December
Onset, 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
Onset, MA
- Average cloud cover in December: 48
The month with the most cloud cover is March (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in December
Onset, 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).
Onset, Massachusetts, USA
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