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
Onset of December comes with a temperature decline, the average high falling from a cool 51.4°F (10.8°C) in November to an icy 41.9°F (5.5°C). Throughout December, the temperature falls to an average low of 30.9°F (-0.6°C).Humidity
In December, the average relative humidity is 78%.Rainfall
In Forest Grove, during December, the rain falls for 10.9 days and regularly aggregates up to 2.76" (70mm) of precipitation. In Forest Grove, during the entire year, the rain falls for 158.6 days and collects up to 28.31" (719mm) of precipitation.Snowfall
Months with snowfall in Forest Grove are January through May, October through December. In Forest Grove, in December, during 4.1 snowfall days, 2.13" (54mm) of snow is typically accumulated. Throughout the year, there are 24.6 snowfall days, and 10.24" (260mm) 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 4:34 pm. On the last day of December, sunrise is at 7:22 am and sunset at 4:44 pm EST.
Sunshine
In December, the average sunshine 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 of 2, and less, symbolizes a low health risk from exposure to the Sun's UV rays for the average person.Note: A maximum high UV index of 2 in December translates into the following recommendations:
Children, babies, and those with sensitive skin should always be shielded from long periods of sun exposure. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days. Notice! The UV radiation of the Sun can be intensified nearly twofold due to the reflective quality of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is it cold during December?
What is the average humidity in December?
How much does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Forest Grove have in December?
When are sunrise and sunset in December?
How many hours of sunshine does Forest Grove have in December?
When is the lowest UV index?
How high is the UV index in December?
Average temperature in December
Forest Grove, PA
- Average high temperature in December: 41.9°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 (35.6°F).
- Average low temperature in December: 30.9°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (23.4°F).
Average pressure in December
Forest Grove, 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
Forest Grove, PA
- Average wind speed in December: 7.6mph
The windiest month (with the highest average wind speed) is March (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.2mph).
Average humidity in December
Forest Grove, PA
- Average humidity in December: 78%
The months with the highest relative humidity are February and October (79%).
The month with the lowest relative humidity is April (73%).
Average rainfall in December
Forest Grove, PA
- Average rainfall in December: 2.76"
The wettest month (with the highest rainfall) is July (2.87").
The driest month (with the least rainfall) is September (1.65").
Average rainfall days in December
Forest Grove, PA
- Average rainfall days in December: 10.9 days
The month with the highest number of rainy days is July (17.3 days).
The month with the least rainy days is January (8.7 days).
Average snowfall in December
Forest Grove, PA
- Average snowfall in December: 2.13"
The month with the highest snowfall is March (2.76").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Forest Grove, PA
- Average snowfall days in December: 4.1 days
The month with the highest number of snowfall days is January (7.9 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Forest Grove, 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 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in December
Forest Grove, PA
- Average sunshine days in December: 16.6 days
The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is June (11 days).
Average UV index in December
Forest Grove, 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
Forest Grove, PA
- Average cloud cover in December: 48
The months with the most cloud cover are February and December (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in December
Forest Grove, 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).
Forest Grove, Pennsylvania, USA
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