December weather forecast
Grassflat, PA

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Weather in December

December, the first month of the winter in Grassflat, is also a wintry month, with an average temperature varying between 36.3°F (2.4°C) and 25.9°F (-3.4°C).

Temperature

The arrival of December indicates a decrease in the average high-temperature, moving from a frosty 45.9°F (7.7°C) in November to a cold 36.3°F (2.4°C). In the month of December, Grassflat experiences an average low-temperature of 25.9°F (-3.4°C).

Humidity

In December, the average relative humidity is 84%.

Rainfall

In Grassflat, during December, the rain falls for 11.4 days and regularly aggregates up to 1.57" (40mm) of precipitation. Throughout the year, there are 159 rainfall days, and 23.46" (596mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, October through December. In Grassflat, in December, during 13.8 snowfall days, 4.13" (105mm) of snow is typically accumulated. In Grassflat, during the entire year, snow falls for 67.7 days and aggregates up to 23.54" (598mm) of snow.

Daylight

December has the shortest days of the year, with an average of 9h and 18min of daylight.
On the first day of December, sunrise is at 7:18 am and sunset at 4:44 pm. On the last day of the month, sunrise is at 7:37 am and sunset at 4:54 pm EST.

Sunshine

In Grassflat, the average sunshine in December is 3.5h.

UV index

December is the month with the lowest UV index, with an average maximum UV index of 1. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: In December, an average UV index of 1 transforms into the following instructions:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck. Take precaution! The reflection from snow can almost double the UV radiation of the Sun.

Frequently asked questions

How cold is December?

During December, Grassflat experiences an average high-temperature of 36.3°F (2.4°C) and a low-temperature of 25.9°F (-3.4°C). The average heat index (a.k.a. 'feels like', 'apparent temperature'), which combines air temperature and relative humidity, in July is estimated at 86°F (30°C).

What is the average humidity in December in Grassflat?

In Grassflat, Pennsylvania, the average relative humidity in December is 84%.

How many days does it rain in December?

In Grassflat, in December, it is raining for 11.4 days, with typically 1.57" (40mm) of accumulated precipitation.

How much does it snow in December?

In December, it is snowing for 13.8 days. Throughout December, 4.13" (105mm) of snow is accumulated.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 9h and 18min of daylight.

How many hours of daylight does Grassflat have in December?

In Grassflat, the average day length in December is 9h and 17min.

When are sunrise and sunset in December?

On the first day of December in Grassflat, sunrise is at 7:18 am and sunset at 4:44 pm. On the last day of the month, sunrise is at 7:37 am and sunset at 4:54 pm EST.

How long on average sun shines in December in Grassflat?

In Grassflat, the average sunshine duration in December is 3.5h.

What is the month with the lowest UV index?

December is the month with the lowest UV index, with an average maximum UV index of 1.

How high is the UV index in December in Grassflat?

In December, the average daily maximum UV index is 1. A UV Index value of 2, and less, symbolizes a low health threat from exposure to Sun's UV rays.
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
Grassflat, PA

Average temperature in December - Grassflat, PA
  • Average high temperature in December: 36.3°F

The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (30.6°F).

  • Average low temperature in December: 25.9°F

The month with the highest average low temperature is July (59.2°F).
The coldest month (with the lowest average low temperature) is January (18°F).

Average pressure in December
Grassflat, PA

Average pressure in December - Grassflat, 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 (29.95"Hg).

Average wind speed in December
Grassflat, PA

Average wind speed in December - Grassflat, 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 (5mph).

Average humidity in December
Grassflat, PA

Average humidity in December - Grassflat, PA
  • Average humidity in December: 84%

The month with the highest relative humidity is February (85%).
The month with the lowest relative humidity is July (76%).

Average rainfall in December
Grassflat, PA

Average rainfall in December - Grassflat, PA
  • Average rainfall in December: 1.57"

The wettest month (with the highest rainfall) is May (2.87").
The driest month (with the least rainfall) is November (1.42").

Average rainfall days in December
Grassflat, PA

Average rainfall days in December - Grassflat, PA
  • Average rainfall days in December: 11.4 days

The month with the highest number of rainy days is May (17.9 days).
The month with the least rainy days is January (8.1 days).

Average snowfall in December
Grassflat, PA

Average snowfall in December - Grassflat, PA
  • Average snowfall in December: 4.13"

The month with the highest snowfall is January (6.02").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Grassflat, PA

Average snowfall days in December - Grassflat, PA
  • Average snowfall days in December: 13.8 days

The month with the highest number of snowfall days is January (18.3 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in December / Average sunshine in December - Grassflat, PA
  • Average daylight in December: 9h and 2min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in December: 3h and 3min

The months with the most sunshine are July and August (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 24min).

Average sunshine days in December
Grassflat, PA

Average sunshine days in December - Grassflat, PA
  • Average sunshine days in December: 10.5 days

The month with the most sunshine days is September (15.4 days).
The month with the least sunshine days is February (8.7 days).

Average UV index in December
Grassflat, PA

Average UV index in December - Grassflat, PA
  • Average UV index in December: 1

The months with the highest UV index are May, June, July and August (UV index 5).
The month with the lowest UV index is December (UV index 1).

Average cloud cover in December
Grassflat, PA

Average cloud cover in December - Grassflat, PA
  • Average cloud cover in December: 64

The month with the most cloud cover is January (Cloud cover 67).
The months with the least cloud cover are July and August (Cloud cover 38).

Average visibility in December
Grassflat, PA

Average visibility in December - Grassflat, PA
  • Average visibility in December: 5mi

The months with the highest visibility are January, March, April, May, June, July, August, October, November and December (5mi).
The months with the lowest visibility are February and September (4mi).

Grassflat, Pennsylvania, USA

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