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
Stepping into December, Cornwall observes a temperature decline, with the average high falling from November's frosty 49.5°F (9.7°C) to a wintry 40.3°F (4.6°C). During December, Cornwall's temperature falls to a steady low-temperature average of 29.3°F (-1.5°C).Humidity
In Cornwall, the average relative humidity in December is 80%.Rainfall
In Cornwall, in December, during 9.2 rainfall days, 1.1" (28mm) of precipitation is typically accumulated. In Cornwall, during the entire year, the rain falls for 137.4 days and collects up to 16.26" (413mm) of precipitation.Snowfall
January through May, October through December are months with snowfall. In Cornwall, during December, snow falls for 3.3 days and regularly aggregates up to 0.98" (25mm) of snow. Throughout the year, there are 19.5 snowfall days, and 6.69" (170mm) of snow is accumulated.Daylight
The month with the shortest days in Cornwall is December, with an average of 9h and 24min of daylight.On the first day of December, sunrise is at 7:09 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:28 am and sunset at 4:49 pm EST.
Sunshine
The average sunshine in December is 4.6h.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 minimal health vulnerability from exposure to the Sun's UV rays for the average person.Note: In December, the UV index of 2 transforms into the following advice:
Many can withstand an hour in the sun without burning, yet children must always have protection against sunlight. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage. Mark this! Snow reflection can nearly double the UV radiation intensity from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is it cold during December?
What is the average humidity in December?
How many days does it rain in December?
How many days does it snow 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?
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
Cornwall, PA
- Average high temperature in December: 40.3°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.8°F).
- Average low temperature in December: 29.3°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).
Average pressure in December
Cornwall, 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
Cornwall, PA
- Average wind speed in December: 8mph
The windiest month (with the highest average wind speed) is March (8.8mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in December
Cornwall, PA
- Average humidity in December: 80%
The months with the highest relative humidity are February, May and October (81%).
The month with the lowest relative humidity is April (76%).
Average rainfall in December
Cornwall, PA
- Average rainfall in December: 1.1"
The wettest month (with the highest rainfall) is August (2.13").
The driest month (with the least rainfall) is February (0.94").
Average rainfall days in December
Cornwall, PA
- Average rainfall days in December: 9.2 days
The month with the highest number of rainy days is May (15.9 days).
The month with the least rainy days is January (6.7 days).
Average snowfall in December
Cornwall, PA
- Average snowfall in December: 0.98"
The month with the highest snowfall is January (1.97").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Cornwall, PA
- Average snowfall days in December: 3.3 days
The month with the highest number of snowfall days is January (5.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Cornwall, 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 24min).
- Average sunshine in December: 4h and 4min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 30min).
Average sunshine days in December
Cornwall, PA
- Average sunshine days in December: 18.7 days
The month with the most sunshine days is January (20.3 days).
The month with the least sunshine days is May (11.5 days).
Average UV index in December
Cornwall, PA
- Average UV index in December: 2
The months with the highest UV index are May, 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
Cornwall, PA
- Average cloud cover in December: 51
The months with the most cloud cover are February and December (Cloud cover 51).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Cornwall, PA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, June, July, November and December (6mi).
The months with the lowest visibility are May, August, September and October (5mi).
Cornwall, Pennsylvania, USA
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