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
December's arrival comes with a decrease in the average high-temperature, moving from a chilly 48°F (8.9°C) in November to an icy 38.8°F (3.8°C). Saint Clair experiences an average temperature drop to a subzero cold 27.7°F (-2.4°C) during December nights.Humidity
In December, the average relative humidity is 81%.Rainfall
In Saint Clair, in December, it is raining for 13.5 days, with typically 2.87" (73mm) of accumulated precipitation. Throughout the year, there are 172.9 rainfall days, and 34.21" (869mm) of precipitation is accumulated.Snowfall
January through May, October through December are months with snowfall. In Saint Clair, during December, snow falls for 6.9 days and regularly aggregates up to 2.8" (71mm) of snow. In Saint Clair, during the entire year, snow falls for 39.7 days and aggregates up to 20.47" (520mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 18min of daylight.On the first day of the month, sunrise is at 7:10 am and sunset at 4:38 pm. On the last day of December, sunrise is at 7:28 am and sunset at 4:47 pm EST.
Sunshine
The months with the least sunshine are January, February and December, with an average of 4.4h 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 threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: The daily maximum UV index of 2 in December interprets into the following advice:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. Stay safe from the Sun's strongest UV rays by limiting exposure during midday. Opt for tightly woven and loose clothing to enhance protection from the Sun. Remember this! The UV radiation of the Sun can be nearly doubled by the reflective properties of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold does it get in December?
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 Saint Clair have in December?
What time are sunrise and sunset in December?
What are the months with the least sunshine?
How long on average sun shines in December?
When is the lowest UV index?
What is the UV index reading in December?
Average temperature in December
Saint Clair, PA
- Average high temperature in December: 38.8°F
The warmest month (with the highest average high temperature) is July (81.5°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 (61.3°F).
The coldest month (with the lowest average low temperature) is January (20.5°F).
Average pressure in December
Saint Clair, 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
Saint Clair, PA
- Average wind speed in December: 7.7mph
The windiest month (with the highest average wind speed) is March (8.4mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in December
Saint Clair, PA
- Average humidity in December: 81%
The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is April (77%).
Average rainfall in December
Saint Clair, PA
- Average rainfall in December: 2.87"
The wettest month (with the highest rainfall) is May (3.39").
The driest month (with the least rainfall) is September (2.09").
Average rainfall days in December
Saint Clair, PA
- Average rainfall days in December: 13.5 days
The month with the highest number of rainy days is May (18.7 days).
The months with the least rainy days are January and November (10.8 days).
Average snowfall in December
Saint Clair, PA
- Average snowfall in December: 2.8"
The month with the highest snowfall is January (5.47").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Saint Clair, PA
- Average snowfall days in December: 6.9 days
The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Saint Clair, 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 30min).
The months with the least sunshine are January, February and December (Average sunshine: 4h and 24min).
Average sunshine days in December
Saint Clair, PA
- Average sunshine days in December: 14.2 days
The month with the most sunshine days is November (16.3 days).
The month with the least sunshine days is May (9.6 days).
Average UV index in December
Saint Clair, PA
- Average UV index in December: 2
The month with the highest UV index is 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
Saint Clair, PA
- Average cloud cover in December: 53
The months with the most cloud cover are February and December (Cloud cover 53).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Saint Clair, PA
- Average visibility in December: 5mi
The month with the highest visibility is April (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October, November and December (5mi).
Saint Clair, Pennsylvania, USA
Weather forecast for your location
2. Allow the app to use your location