December weather forecast
Union Gap, WA

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Weather in December

December, the first month of the winter in Union Gap, is also a wintry month, with an average temperature fluctuating between 36.9°F (2.7°C) and 25.5°F (-3.6°C).

Temperature

The lowest temperatures are recorded in December, with averages reaching a high of 36.9°F (2.7°C) and a low of 25.5°F (-3.6°C).

Humidity

In Union Gap, the average relative humidity in December is 80%.

Rainfall

In Union Gap, in December, it is raining for 9.1 days, with typically 0.83" (21mm) of accumulated precipitation. In Union Gap, during the entire year, the rain falls for 82.2 days and collects up to 5.43" (138mm) of precipitation.

Snowfall

Months with snowfall are January through March, September, November and December. December is the month with the most snowfall in Union Gap, Washington. Snow falls for 5.4 days and accumulates 2.76" (70mm) of snow.

Daylight

With an average of 8h and 36min of daylight, December has the shortest days of the year in Union Gap.
On the first day of the month, sunrise is at 7:26 am and sunset at 4:16 pm. On the last day of December, in Union Gap, sunrise is at 7:45 am and sunset at 4:24 pm PST.

Sunshine

In Union Gap, the average sunshine in December is 5.9h.

UV index

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The maximum daily UV index, 2 in December, converts into the following recommendations:
Although the majority can endure up to an hour in the sun without burns, children always require sun protection. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Take precaution! The reflection from snow can almost double the UV radiation of the Sun.
Updated: Feb 14, 2024 | Published by: Weather U.S. | About Us / Weather Forecasting / Data Sources

Frequently asked questions

What time of the year is the coldest in Union Gap?

December brings the lowest temperatures in Union Gap, with an average high of 36.9°F (2.7°C) and an average low of 25.5°F (-3.6°C).

How cold is December in Union Gap?

December temperatures in Union Gap vary between a high-temperature of 36.9°F (2.7°C) and a low-temperature of 25.5°F (-3.6°C).

What is the average humidity in December in Union Gap?

In December, the average relative humidity in Union Gap is 80%.

How much does it rain in Union Gap in December?

In Union Gap, in December, during 9.1 rainfall days, 0.83" (21mm) of precipitation is typically accumulated.

When does it snow the most in Union Gap?

December is the month with the most snowfall. Snow falls for 5.4 days and accumulates 2.76" (70mm) of snow.

How much does it snow in Union Gap in December?

In Union Gap, during December, snow falls for 5.4 days and regularly aggregates up to 2.76" (70mm) of snow.

What is the month with the shortest days in Union Gap?

With an average of 8h and 36min of daylight, December has the shortest days of the year.

What is the average length of the day in December in Union Gap?

In December, the average day length in Union Gap is 8h and 38min.

When are sunrise and sunset in December in Union Gap?

In December, on the first day of the month, sunrise is at 7:26 am and sunset at 4:16 pm. On the last day of the month, sunrise is at 7:45 am and sunset at 4:24 pm PST.

How many hours of sunshine does Union Gap have in December?

The average sunshine duration in December is 5.9h.

What is the month with the lowest UV index in Union Gap?

The months with the lowest UV index in Union Gap, Washington, are January, February, November and December, with an average maximum UV index of 2.

What is the UV index intensity in December in Union Gap?

In December, the average daily maximum UV index in Union Gap, Washington, is 2. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to 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
Union Gap, WA

Average temperature in December - Union Gap, WA
  • Average high temperature in December: 36.9°F

The warmest month (with the highest average high temperature) is August (86.5°F).
The month with the lowest average high temperature is December (36.9°F).

  • Average low temperature in December: 25.5°F

The month with the highest average low temperature is August (60.3°F).
The coldest month (with the lowest average low temperature) is December (25.5°F).

Average pressure in December
Union Gap, WA

Average pressure in December - Union Gap, WA
  • Average pressure in December: 30.14"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.93"Hg).

Average wind speed in December
Union Gap, WA

Average wind speed in December - Union Gap, WA
  • Average wind speed in December: 4.4mph

The windiest month (with the highest average wind speed) is June (7.1mph).
The calmest month (with the lowest average wind speed) is December (4.4mph).

Average humidity in December
Union Gap, WA

Average humidity in December - Union Gap, WA
  • Average humidity in December: 80%

The month with the highest relative humidity is January (81%).
The months with the lowest relative humidity are July and August (39%).

Average rainfall in December
Union Gap, WA

Average rainfall in December - Union Gap, WA
  • Average rainfall in December: 0.83"

The wettest month (with the highest rainfall) is January (0.87").
The driest month (with the least rainfall) is July (0.08").

Average rainfall days in December
Union Gap, WA

Average rainfall days in December - Union Gap, WA
  • Average rainfall days in December: 9.1 days

The month with the highest number of rainy days is March (10.8 days).
The month with the least rainy days is August (2 days).

Average snowfall in December
Union Gap, WA

Average snowfall in December - Union Gap, WA
  • Average snowfall in December: 2.76"

The month with the highest snowfall is December (2.76").
The months with the least snowfall are April, May, June, July, August and October (0").

Average snowfall days in December
Union Gap, WA

Average snowfall days in December - Union Gap, WA
  • Average snowfall days in December: 5.4 days

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

Average daylight in December /
Average sunshine in December
Union Gap, WA

Average daylight in December / Average sunshine in December - Union Gap, WA
  • Average daylight in December: 8h and 4min

The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).

  • Average sunshine in December: 5h and 5min

The months with the most sunshine are July and August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 5h and 36min).

Average sunshine days in December
Union Gap, WA

Average sunshine days in December - Union Gap, WA
  • Average sunshine days in December: 17.3 days

The month with the most sunshine days is July (27.5 days).
The month with the least sunshine days is February (15.8 days).

Average UV index in December
Union Gap, WA

Average UV index in December - Union Gap, WA
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in December
Union Gap, WA

Average cloud cover in December - Union Gap, WA
  • Average cloud cover in December: 37

The month with the most cloud cover is January (Cloud cover 40).
The months with the least cloud cover are July and August (Cloud cover 9).

Average visibility in December
Union Gap, WA

Average visibility in December - Union Gap, WA
  • Average visibility in December: 6mi

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

Union Gap, Washington, USA

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