December weather forecast
Exton, PA

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Weather in December

Closing the year in Exton, December brings a pronounced onset of winter, dropping the temperature between 31.1°F (-0.5°C) and 42.3°F (5.7°C). The city experiences increased snowfall with 0.79" (20mm) registered over more than two days of the month. As the days shorten further, the chilling winds add to the icy ambiance. Despite the cold, a fair amount of sunshine peeps through casting a shimmering glow on the snow-dusted cityscape. The month provides the city with a picturesque white Christmas, ending the year with a festive spirit.

Temperature

The onset of December coincides with a reduction in the average high-temperature, falling from a fresh 51.4°F (10.8°C) in November to an icy 42.3°F (5.7°C). December brings an average low-temperature of 31.1°F (-0.5°C) to Exton.

Humidity

The average relative humidity in December is 78%.

Rainfall

In December, the rain falls for 7.7 days. Throughout December, 1.14" (29mm) of precipitation is accumulated. In Exton, during the entire year, the rain falls for 124.6 days and collects up to 14.25" (362mm) of precipitation.

Snowfall

Months with snowfall are January through May, November and December. In December, it is snowing for 2.2 days. Throughout December, 0.79" (20mm) of snow is accumulated. In Exton, during the entire year, snow falls for 18.5 days and aggregates up to 5.51" (140mm) of snow.

Daylight

With an average of 9h and 24min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 7:05 am and sunset at 4:37 pm. On the last day of December, sunrise is at 7:24 am and sunset at 4:47 pm EST.

Sunshine

In December, the average sunshine is 4.8h.

UV index

The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health hazard from exposure to the Sun's UV radiation for the ordinary person.
Note: In December, a daily maximum UV index of 2 leads to the following instructions:
Protection from prolonged sun exposure is necessary for babies, children, and individuals with sensitive skin. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. To cut down UV radiation exposure by about half, sport a wide-brim hat. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.
Updated: Aug 15, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December?

The average high-temperature, in December, in Exton, is 42.3°F (5.7°C), while the average low-temperature is 31.1°F (-0.5°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), which factors the actual air temperature with the relative humidity, in August is evaluated at 87.8°F (31°C).

What is the average humidity in December in Exton?

The average relative humidity in December is 78%.

How many days does it rain in December?

In Exton, in December, during 7.7 rainfall days, 1.14" (29mm) of precipitation is typically accumulated.

How much does it snow in December?

In Exton, Pennsylvania, in December, snow falls for 2.2 days, with typically accumulated 0.79" (20mm) of snow.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 9h and 24min of daylight.

How many hours of daylight does Exton have in December?

The average day length in December is 9h and 23min.

When are sunrise and sunset in December?

On the first day of December, sunrise is at 7:05 am and sunset at 4:37 pm. On the last day of the month, sunrise is at 7:24 am and sunset at 4:47 pm EST.

How long on average sun shines in December?

In December, the average sunshine duration is 4.8h.

What is the month with the lowest UV index?

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Exton.

What is the UV index reading in December in Exton?

In December, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Exton, PA

Average temperature in December - Exton, PA
  • Average high temperature in December: 42.3°F

The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is January (36.1°F).

  • Average low temperature in December: 31.1°F

The month with the highest average low temperature is July (67.5°F).
The coldest month (with the lowest average low temperature) is January (24.3°F).

Average pressure in December
Exton, PA

Average pressure in December - Exton, PA
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

Average wind speed in December
Exton, PA

Average wind speed in December - Exton, PA
  • Average wind speed in December: 7.9mph

The windiest month (with the highest average wind speed) is March (8.5mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).

Average humidity in December
Exton, PA

Average humidity in December - Exton, PA
  • Average humidity in December: 78%

The months with the highest relative humidity are February and October (79%).
The months with the lowest relative humidity are April and July (73%).

Average rainfall in December
Exton, PA

Average rainfall in December - Exton, PA
  • Average rainfall in December: 1.14"

The wettest month (with the highest rainfall) is August (1.89").
The driest month (with the least rainfall) is January (0.79").

Average rainfall days in December
Exton, PA

Average rainfall days in December - Exton, PA
  • Average rainfall days in December: 7.7 days

The month with the highest number of rainy days is July (15.1 days).
The month with the least rainy days is January (5 days).

Average snowfall in December
Exton, PA

Average snowfall in December - Exton, PA
  • Average snowfall in December: 0.79"

The month with the highest snowfall is March (1.57").
The months with the least snowfall are June, July, August, September and October (0").

Average snowfall days in December
Exton, PA

Average snowfall days in December - Exton, PA
  • Average snowfall days in December: 2.2 days

The month with the highest number of snowfall days is January (5.4 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in December /
Average sunshine in December
Exton, PA

Average daylight in December / Average sunshine in December - Exton, 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 5min

The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 30min).

Average sunshine days in December
Exton, PA

Average sunshine days in December - Exton, PA
  • Average sunshine days in December: 20.5 days

The month with the most sunshine days is November (21.7 days).
The month with the least sunshine days is June (13.3 days).

Average UV index in December
Exton, PA

Average UV index in December - Exton, PA
  • Average UV index in December: 2

The months with the highest UV index are May, June, 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
Exton, PA

Average cloud cover in December - Exton, PA
  • Average cloud cover in December: 49

The month with the most cloud cover is February (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 33).

Average visibility in December
Exton, PA

Average visibility in December - Exton, PA
  • Average visibility in December: 6mi

The months with the highest visibility are January, February, March, April, June, July, August, October, November and December (6mi).
The months with the lowest visibility are May and September (5mi).

Exton, Pennsylvania, USA

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