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 comes with a drop in the average high-temperature, falling from November's frosty 48.9°F (9.4°C) to a wintry 39.2°F (4°C). During December, Southwest sees a mean low-temperature of 27.7°F (-2.4°C).Humidity
In December, the average relative humidity in Southwest, Pennsylvania, is 84%.Rainfall
In Southwest, in December, it is raining for 13.1 days, with typically 3.03" (77mm) of accumulated precipitation. Throughout the year, in Southwest, there are 185.4 rainfall days, and 34.02" (864mm) of precipitation is accumulated.Snowfall
Months with snowfall in Southwest are January through May, October through December. In Southwest, during December, snow falls for 12.8 days and regularly aggregates up to 6.1" (155mm) of snow. Throughout the year, in Southwest, there are 63.2 snowfall days, and 29.02" (737mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 24min of daylight.On the first day of December in Southwest, sunrise is at 7:21 am and sunset at 4:52 pm. On the last day of the month, sunrise is at 7:40 am and sunset at 5:02 pm EST.
Sunshine
The average sunshine in December is 3.6h.UV index
January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Southwest. A UV Index reading of 2, and below, represents a minimal health hazard from unsafe exposure to UV radiation for average individuals.Note: The daily high UV index of 2 during December translates into the following recommendations:
It is important to always shield children, babies, and individuals with sensitive skin from prolonged exposure to the sun. Direct exposure to the Sun during its peak hours around mid-day should be minimized for safety. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Attention! Nearly twice the Sun's UV radiation can be reflected by snow.
Frequently asked questions
Is it cold in Southwest during December?
What is the average humidity in December in Southwest?
How many days does it rain in December in Southwest?
How much does it snow in Southwest in December?
What is the month with the shortest days in Southwest?
What is the average length of the day in December in Southwest?
What time are sunrise and sunset in December in Southwest?
How many hours of sunshine does Southwest have in December?
What is the month with the lowest UV index in Southwest?
What is the UV index reading in December in Southwest?
Average temperature in December
Southwest, PA
- Average high temperature in December: 39.2°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.3°F).
- Average low temperature in December: 27.7°F
The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is January (20.3°F).
Average pressure in December
Southwest, PA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed in December
Southwest, PA
- Average wind speed in December: 7.9mph
The windiest month (with the highest average wind speed) is January (8.5mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in December
Southwest, PA
- Average humidity in December: 84%
The months with the highest relative humidity are January and February (85%).
The months with the lowest relative humidity are April, July and August (77%).
Average rainfall in December
Southwest, PA
- Average rainfall in December: 3.03"
The wettest month (with the highest rainfall) is May (3.66").
The driest month (with the least rainfall) is November (2.01").
Average rainfall days in December
Southwest, PA
- Average rainfall days in December: 13.1 days
The month with the highest number of rainy days is May (22 days).
The month with the least rainy days is January (9.8 days).
Average snowfall in December
Southwest, PA
- Average snowfall in December: 6.1"
The month with the highest snowfall is January (7.09").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Southwest, PA
- Average snowfall days in December: 12.8 days
The month with the highest number of snowfall days is January (17.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Southwest, 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: 3h and 4min
The month with the most sunshine is August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).
Average sunshine days in December
Southwest, PA
- Average sunshine days in December: 9.7 days
The month with the most sunshine days is November (13.5 days).
The month with the least sunshine days is January (6.5 days).
Average UV index in December
Southwest, 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
Southwest, PA
- Average cloud cover in December: 64
The month with the most cloud cover is January (Cloud cover 69).
The month with the least cloud cover is August (Cloud cover 35).
Average visibility in December
Southwest, PA
- Average visibility in December: 5mi
The month with the highest visibility is April (6mi).
The months with the lowest visibility are January and February (4mi).
Southwest, Pennsylvania, USA
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