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
A shift in Norristown's weather is observed as November turns into December, with the average high temperature reducing from a fresh 51.6°F (10.9°C) to a wintry 42.6°F (5.9°C). Throughout December, an average nighttime temperature of 30.9°F (-0.6°C) is experienced in Norristown, Pennsylvania.Humidity
In December, the average relative humidity is 78%.Rainfall
In Norristown, Pennsylvania, in December, it is raining for 8.6 days, with typically 1.22" (31mm) of accumulated precipitation. Throughout the year, there are 138.2 rainfall days, and 15.59" (396mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through March, May and December. December is the first month it typically snows. Throughout December, in the average 2.6 snowfall days, it receives 0.35" (9mm) of snow. Throughout the year, there are 15.8 snowfall days, and 2.13" (54mm) 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, sunrise is at 7:04 am and sunset at 4:36 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 4:45 pm EST.
Sunshine
The average sunshine in December is 5h.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 value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for the average person.Note: In December, the maximum UV index of 2 transforms into these recommendations:
Most individuals can handle sun exposure for up to an hour without burning, but children must always be shielded from sun exposure. Avoiding the Sun during its peak radiation time around midday is a healthy practice. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes. Be attentive! The reflective property of snow can nearly double the Sun's UV radiation.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is December?
What is the average humidity in December?
How much does it rain in December?
When does it start to snow?
What is the month with the shortest days?
What is the average length of the day in December?
When is the sunrise / sunset in December?
How long on average sun shines in December?
What are the months with the lowest UV index?
What is the UV index intensity in December?
Average temperature in December
Norristown, PA
- Average high temperature in December: 42.6°F
The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (36.7°F).
- Average low temperature in December: 30.9°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
Norristown, 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
Norristown, PA
- Average wind speed in December: 7.5mph
The windiest month (with the highest average wind speed) is March (8.3mph).
The calmest months (with the lowest average wind speed) are July and August (5.3mph).
Average humidity in December
Norristown, 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 (72%).
Average rainfall in December
Norristown, PA
- Average rainfall in December: 1.22"
The wettest month (with the highest rainfall) is July (1.89").
The driest month (with the least rainfall) is February (0.91").
Average rainfall days in December
Norristown, PA
- Average rainfall days in December: 8.6 days
The month with the highest number of rainy days is May (16 days).
The month with the least rainy days is November (7.4 days).
Average snowfall in December
Norristown, PA
- Average snowfall in December: 0.35"
The months with the highest snowfall are February and March (0.55").
The months with the least snowfall are April, June, July, August, September, October and November (0").
Average snowfall days in December
Norristown, PA
- Average snowfall days in December: 2.6 days
The month with the highest number of snowfall days is January (5.2 days).
The months with the least snowfall days are April, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Norristown, 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: 5h and 0min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).
Average sunshine days in December
Norristown, PA
- Average sunshine days in December: 19.9 days
The month with the most sunshine days is November (20.5 days).
The months with the least sunshine days are May and June (12.8 days).
Average UV index in December
Norristown, 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
Norristown, PA
- Average cloud cover in December: 47
The month with the most cloud cover is February (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Norristown, 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).
Norristown, Pennsylvania, USA
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