December weather forecast
Black Diamond, WA

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Weather in December

December, the first month of the winter in Black Diamond, is still a cold month, with an average temperature ranging between max 40.8°F (4.9°C) and min 32°F (0°C).

Temperature

December, characterized by an average high temperature of 40.8°F (4.9°C) and a low temperature of 32°F (0°C), is generally the coldest month.

Humidity

In December, the average relative humidity is 85%.

Rainfall

December is the month with the most rainfall in Black Diamond. Rain falls for 18.7 days and accumulates 5.43" (138mm) of precipitation.

Snowfall

Months with snowfall in Black Diamond are January through April, November and December. In Black Diamond, in December, snow falls for 3.9 days, with typically accumulated 1.65" (42mm) of snow. In Black Diamond, during the entire year, snow falls for 19.7 days and aggregates up to 11.5" (292mm) of snow.

Daylight

With an average of 8h and 30min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 7:35 am and sunset at 4:19 pm. On the last day of December, sunrise is at 7:54 am and sunset at 4:27 pm PST.

Sunshine

The months with the least sunshine are January and December, with an average of 4.1h of sunshine.

UV index

The average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a minimal health hazard from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum UV index of 2 during December leads to these instructions:
In contrast to children, who must always be shielded from the sun, most people can tolerate up to an hour of sun exposure without any burns. For skin protection, it's recommended to minimize Sun exposure during its peak hours around midday. To cut down UV radiation exposure by about half, sport a wide-brim hat. Forewarned is forearmed! The Sun's UV radiation can be almost doubled in intensity by snow reflection.
Updated: Feb 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the coldest months in Black Diamond?

Black Diamond's temperature records reveal December as the coldest month, marked by average highs of 40.8°F (4.9°C) and lows of 32°F (0°C).

Is it cold in Black Diamond during December?

In December, the average high-temperature and low-temperature are 40.8°F (4.9°C) and 32°F (0°C) respectively.

What is the average humidity in December in Black Diamond?

In December, the average relative humidity is 85%.

What is the wettest month in Black Diamond?

The month with the most rainfall in Black Diamond is December, when the rain falls for 18.7 days and typically aggregates up to 5.43" (138mm) of precipitation.

How many days does it rain in December in Black Diamond?

In Black Diamond, Washington, in December, during 18.7 rainfall days, 5.43" (138mm) of precipitation is typically accumulated.

How much does it snow in Black Diamond in December?

In Black Diamond, in December, during 3.9 snowfall days, 1.65" (42mm) of snow is typically accumulated.

What is the month with the shortest days in Black Diamond?

With an average of 8h and 30min of daylight, December has the shortest days of the year.

How many hours of daylight does Black Diamond have in December?

The average day length in December in Black Diamond is 8h and 33min.

What time are sunrise and sunset in December in Black Diamond?

In December, on the first day of the month, sunrise is at 7:35 am and sunset at 4:19 pm. On the last day of the month, in Black Diamond, sunrise is at 7:54 am and sunset at 4:27 pm PST.

What is the month with the least sunshine in Black Diamond?

January and December, with an average of 4.1h of sunshine, are months with the least sunshine.

How many hours of sunshine does Black Diamond have in December?

The average sunshine duration in December is 4.1h.

What is the UV index reading in December in Black Diamond?

The average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a minimal hazard to health 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
Black Diamond, WA

Average temperature in December - Black Diamond, WA
  • Average high temperature in December: 40.8°F

The warmest month (with the highest average high temperature) is August (75.4°F).
The month with the lowest average high temperature is December (40.8°F).

  • Average low temperature in December: 32°F

The month with the highest average low temperature is August (50.2°F).
The coldest month (with the lowest average low temperature) is February (31.6°F).

Average pressure in December
Black Diamond, WA

Average pressure in December - Black Diamond, WA
  • Average pressure in December: 30.09"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are August and September (30"Hg).

Average wind speed in December
Black Diamond, WA

Average wind speed in December - Black Diamond, WA
  • Average wind speed in December: 4.8mph

The windiest month (with the highest average wind speed) is January (5.2mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).

Average humidity in December
Black Diamond, WA

Average humidity in December - Black Diamond, WA
  • Average humidity in December: 85%

The months with the highest relative humidity are January and February (86%).
The month with the lowest relative humidity is July (70%).

Average rainfall in December
Black Diamond, WA

Average rainfall in December - Black Diamond, WA
  • Average rainfall in December: 5.43"

The wettest month (with the highest rainfall) is December (5.43").
The driest month (with the least rainfall) is July (0.59").

Average rainfall days in December
Black Diamond, WA

Average rainfall days in December - Black Diamond, WA
  • Average rainfall days in December: 18.7 days

The month with the highest number of rainy days is March (20.5 days).
The month with the least rainy days is August (6.7 days).

Average snowfall in December
Black Diamond, WA

Average snowfall in December - Black Diamond, WA
  • Average snowfall in December: 1.65"

The month with the highest snowfall is February (4.17").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days in December
Black Diamond, WA

Average snowfall days in December - Black Diamond, WA
  • Average snowfall days in December: 3.9 days

The month with the highest number of snowfall days is February (6 days).
The months with the least snowfall days are June, July, August and October (0 days).

Average daylight in December /
Average sunshine in December
Black Diamond, WA

Average daylight in December / Average sunshine in December - Black Diamond, WA
  • Average daylight in December: 8h and 3min

The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).

  • Average sunshine in December: 4h and 1min

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are January and December (Average sunshine: 4h and 6min).

Average sunshine days in December
Black Diamond, WA

Average sunshine days in December - Black Diamond, WA
  • Average sunshine days in December: 10.3 days

The month with the most sunshine days is August (22 days).
The month with the least sunshine days is February (8.4 days).

Average UV index in December
Black Diamond, WA

Average UV index in December - Black Diamond, WA
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 5).
The month with the lowest UV index is November (UV index 1).

Average cloud cover in December
Black Diamond, WA

Average cloud cover in December - Black Diamond, WA
  • Average cloud cover in December: 57

The months with the most cloud cover are January, February, March and December (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 27).

Average visibility in December
Black Diamond, WA

Average visibility in December - Black Diamond, WA
  • Average visibility in December: 4mi

The months with the highest visibility are July and August (6mi).
The months with the lowest visibility are January, February and December (4mi).

Black Diamond, Washington, USA

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