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 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 beginning of December involves a decrease in the average high-temperature, transitioning from a frosty 48.7°F (9.3°C) in November to a cold 39.4°F (4.1°C). Williamstown's temperature tends to fall to an average low of 28.2°F (-2.1°C) during the nights of December.Humidity
In Williamstown, the average relative humidity in December is 80%.Rainfall
In December, the rain falls for 9.7 days. Throughout December, 1.65" (42mm) of precipitation is accumulated. In Williamstown, during the entire year, the rain falls for 148.4 days and collects up to 25.55" (649mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In Williamstown, during December, snow falls for 4.9 days and regularly aggregates up to 1.3" (33mm) of snow. In Williamstown, during the entire year, snow falls for 26.2 days and aggregates up to 12.32" (313mm) of snow.Daylight
December has the shortest days of the year, with an average of 9h and 18min of daylight.On the first day of December, sunrise is at 7:11 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:29 am and sunset at 4:49 pm EST.
Sunshine
In December, the average sunshine is 4.4h.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 hazard from exposure to the Sun's UV rays for ordinary individuals.Note: In December, the maximum UV index of 2 suggests this advice:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. The midday Sun can be dangerous due to its intense radiation; always find shade and reduce exposure. To cut down UV radiation exposure by about half, sport a wide-brim hat. Notice! The UV radiation of the Sun can be intensified nearly twofold due to the reflective quality of snow.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is December cold?
What is the average humidity in December?
How much does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Williamstown have in December?
When are sunrise and sunset in December?
How long on average sun shines in December?
What is the month with the lowest UV index in Williamstown?
How high is the UV index in December?
Average temperature in December
Williamstown, PA
- Average high temperature in December: 39.4°F
The warmest month (with the highest average high temperature) is July (82.2°F).
The month with the lowest average high temperature is January (33.4°F).
- Average low temperature in December: 28.2°F
The month with the highest average low temperature is July (62.1°F).
The coldest month (with the lowest average low temperature) is January (20.8°F).
Average pressure in December
Williamstown, PA
- Average pressure in December: 30.1"Hg
The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).
Average wind speed in December
Williamstown, PA
- Average wind speed in December: 7.5mph
The windiest months (with the highest average wind speed) are March and April (8.3mph).
The calmest month (with the lowest average wind speed) is August (4.6mph).
Average humidity in December
Williamstown, PA
- Average humidity in December: 80%
The month with the highest relative humidity is February (82%).
The month with the lowest relative humidity is April (76%).
Average rainfall in December
Williamstown, PA
- Average rainfall in December: 1.65"
The wettest month (with the highest rainfall) is May (2.95").
The driest month (with the least rainfall) is February (1.54").
Average rainfall days in December
Williamstown, PA
- Average rainfall days in December: 9.7 days
The month with the highest number of rainy days is May (17.4 days).
The month with the least rainy days is January (7.2 days).
Average snowfall in December
Williamstown, PA
- Average snowfall in December: 1.3"
The month with the highest snowfall is March (3.43").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Williamstown, PA
- Average snowfall days in December: 4.9 days
The month with the highest number of snowfall days is January (6.9 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Williamstown, PA
- Average daylight in December: 9h and 2min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in December: 4h and 2min
The month with the most sunshine is July (Average sunshine: 10h and 18min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).
Average sunshine days in December
Williamstown, PA
- Average sunshine days in December: 18.1 days
The month with the most sunshine days is November (18.8 days).
The month with the least sunshine days is May (10.8 days).
Average UV index in December
Williamstown, PA
- Average UV index in December: 2
The months with the highest UV index are June and July (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
Williamstown, PA
- Average cloud cover in December: 54
The months with the most cloud cover are February and December (Cloud cover 54).
The month with the least cloud cover is July (Cloud cover 33).
Average visibility in December
Williamstown, PA
- Average visibility in December: 6mi
The months with the highest visibility are January, March, April, June, July, November and December (6mi).
The months with the lowest visibility are February, May, August, September and October (5mi).
Williamstown, Pennsylvania, USA
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