December weather forecastBryn Mawr, PA
December
Weather in December
The first month of the winter, December, is also a frosty month in Bryn Mawr, Pennsylvania, with temperature in the range of an average low of 32°F (0°C) and an average high of 43.2°F (6.2°C).Temperature
December reveals a small adjustment in temperature, transitioning from an average high of a fresh 52°F (11.1°C) in November to a frosty 43.2°F (6.2°C). In December, the temperature drops to an average of 32°F (0°C) at night.Humidity
In Bryn Mawr, the average relative humidity in December is 77%.Rainfall
In Bryn Mawr, during December, the rain falls for 6.5 days and regularly aggregates up to 0.91" (23mm) of precipitation. In Bryn Mawr, during the entire year, the rain falls for 111.8 days and collects up to 9.69" (246mm) of precipitation.Snowfall
January through March, November and December are months with snowfall. In December, in Bryn Mawr, it is snowing for 2.1 days. Throughout December, 0.63" (16mm) of snow is accumulated. Throughout the year, there are 15.1 snowfall days, and 3.66" (93mm) of snow is accumulated.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 7:04 am and sunset at 4:36 pm. On the last day of December, sunrise is at 7:23 am and sunset at 4:46 pm EST.
Sunshine
In December, the average sunshine is 4.9h.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's UV rays for the ordinary person.Note: In December, the maximum UV index of 2 suggests this advice:
While extended sun exposure does not significantly affect most people, those with sensitive skin, children, and infants should always be protected. Given the potency of the midday Sun's UV radiation, one should avoid prolonged exposure. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key. Remember! The Sun's UV radiation can be magnified almost twofold by the reflection of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Bryn Mawr, PA
- Average high temperature in December: 43.2°F
The warmest month (with the highest average high temperature) is July (85.8°F).
The month with the lowest average high temperature is January (36.7°F).
- Average low temperature in December: 32°F
The month with the highest average low temperature is July (68.9°F).
The coldest month (with the lowest average low temperature) is January (25°F).
Average pressure in December
Bryn Mawr, PA
- Average pressure in December: 30.09"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
Bryn Mawr, PA
- Average wind speed in December: 7.8mph
The windiest month (with the highest average wind speed) is March (8.5mph).
The calmest month (with the lowest average wind speed) is August (5.5mph).
Average humidity in December
Bryn Mawr, PA
- Average humidity in December: 77%
The months with the highest relative humidity are February and October (78%).
The months with the lowest relative humidity are April, July and August (71%).
Average rainfall in December
Bryn Mawr, PA
- Average rainfall in December: 0.91"
The wettest months (with the highest rainfall) are July and August (1.14").
The driest month (with the least rainfall) is January (0.55").
Average rainfall days in December
Bryn Mawr, PA
- Average rainfall days in December: 6.5 days
The month with the highest number of rainy days is July (13.3 days).
The month with the least rainy days is January (5.3 days).
Average snowfall in December
Bryn Mawr, PA
- Average snowfall in December: 0.63"
The months with the highest snowfall are February and March (0.98").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
Bryn Mawr, PA
- Average snowfall days in December: 2.1 days
The month with the highest number of snowfall days is January (4.5 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Bryn Mawr, PA
- Average daylight in December: 9h and 24min
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 54min
The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).
Average sunshine days in December
Bryn Mawr, PA
- Average sunshine days in December: 22.2 days
The month with the most sunshine days is November (22.5 days).
The month with the least sunshine days is July (14.9 days).
Average UV index in December
Bryn Mawr, 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, November and December (UV index 2).
Average cloud cover in December
Bryn Mawr, PA
- Average cloud cover in December: 48
The month with the most cloud cover is February (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Bryn Mawr, PA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
