December weather forecast
Hillsboro, OR

The red tree colors of the fall along a road and amid trees in this tranquil neighborhood in Hillsboro, Oregon
The red tree colors of the fall along a road and amid trees in this tranquil neighborhood in Hillsboro, Oregon

Weather in December

December, the first month of the winter in Hillsboro, is still a chilly month, with an average temperature ranging between max 43.9°F (6.6°C) and min 34°F (1.1°C).

Temperature

The coldest month is December, with an average high-temperature of 43.9°F (6.6°C) and an average low-temperature of 34°F (1.1°C).

Humidity

January, February, November and December, with an average relative humidity of 85%, are the most humid months in Hillsboro.

Rainfall

In December, in Hillsboro, the rain falls for 18.8 days. Throughout December, 4.45" (113mm) of precipitation is accumulated. In Hillsboro, during the entire year, the rain falls for 173 days and collects up to 29.49" (749mm) of precipitation.

Snowfall

Months with snowfall in Hillsboro are January through March, November and December. In Hillsboro, in December, snow falls for 0.7 days, with typically accumulated 0.35" (9mm) of snow. Throughout the year, in Hillsboro, Oregon, there are 6.6 snowfall days, and 4.53" (115mm) of snow is accumulated.

Daylight

With an average of 8h and 46min of daylight, December has the shortest days of the year in Hillsboro.
On the first day of December in Hillsboro, sunrise is at 7:31 am and sunset at 4:30 pm. On the last day of the month, sunrise is at 7:51 am and sunset at 4:38 pm PST.

Sunshine

In Hillsboro, the average sunshine in December is 3.9h.

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 value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for average individuals.
Note: The daily maximum UV index of 2 in December interpret into the following advice:
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 solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the coldest month in Hillsboro?

With an average high-temperature of 43.9°F (6.6°C) and an average low-temperature of 34°F (1.1°C), December is the coldest month in Hillsboro, Oregon.

What is the temperature in December in Hillsboro?

In Hillsboro, Oregon, in December, the average high-temperature is 43.9°F (6.6°C), and the average low-temperature is 34°F (1.1°C). The average heat index (a.k.a. 'apparent temperature', 'feels like'), which calculates the temperature value influenced by the moisture in the air, in August is appraised at 84.2°F (29°C).

What are the most humid months in Hillsboro?

The months with the highest humidity in Hillsboro are January, February, November and December, with an average relative humidity of 85%.

What is the average humidity in December in Hillsboro?

In Hillsboro, Oregon, the average relative humidity in December is 85%.

How much does it rain in Hillsboro in December?

In Hillsboro, during December, the rain falls for 18.8 days and regularly aggregates up to 4.45" (113mm) of precipitation.

How much does it snow in Hillsboro in December?

In Hillsboro, in December, during 0.7 snowfall days, 0.35" (9mm) of snow is typically accumulated.

What is the month with the shortest days in Hillsboro?

December has the shortest days of the year in Hillsboro, Oregon, with an average of 8h and 46min of daylight.

How many hours of daylight does Hillsboro have in December?

The average day length in December is 8h and 46min.

When are sunrise and sunset in December in Hillsboro?

In December, on the first day of the month, sunrise is at 7:31 am and sunset at 4:30 pm. On the last day of the month, in Hillsboro, sunrise is at 7:51 am and sunset at 4:38 pm PST.

How long on average sun shines in December in Hillsboro?

In Hillsboro, the average sunshine duration in December is 3.9h.

When is the lowest UV index in Hillsboro?

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

How high is the UV index in December in Hillsboro?

The average daily maximum UV index in December in Hillsboro is 2. A UV Index estimate of 2, and below, represents a low health threat 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
Hillsboro, OR

Average temperature in December - Hillsboro, OR
  • Average high temperature in December: 43.9°F

The warmest month (with the highest average high temperature) is August (81.5°F).
The month with the lowest average high temperature is December (43.9°F).

  • Average low temperature in December: 34°F

The month with the highest average low temperature is August (55.4°F).
The coldest month (with the lowest average low temperature) is December (34°F).

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Average pressure in December
Hillsboro, OR

Average pressure in December - Hillsboro, OR
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are August and September (30.01"Hg).

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Average wind speed in December
Hillsboro, OR

Average wind speed in December - Hillsboro, OR
  • Average wind speed in December: 4.7mph

The windiest month (with the highest average wind speed) is March (5mph).
The calmest months (with the lowest average wind speed) are June, August and September (4.3mph).

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Average humidity in December
Hillsboro, OR

Average humidity in December - Hillsboro, OR
  • Average humidity in December: 85%

The months with the highest relative humidity are January, February, November and December (85%).
The month with the lowest relative humidity is August (64%).

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Average rainfall in December
Hillsboro, OR

Average rainfall in December - Hillsboro, OR
  • Average rainfall in December: 4.45"

The wettest month (with the highest rainfall) is January (4.57").
The driest month (with the least rainfall) is August (0.31").

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Average rainfall days in December
Hillsboro, OR

Average rainfall days in December - Hillsboro, OR
  • Average rainfall days in December: 18.8 days

The month with the highest number of rainy days is March (20.8 days).
The month with the least rainy days is August (4.4 days).

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Average snowfall in December
Hillsboro, OR

Average snowfall in December - Hillsboro, OR
  • Average snowfall in December: 0.35"

The month with the highest snowfall is February (1.81").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in December
Hillsboro, OR

Average snowfall days in December - Hillsboro, OR
  • Average snowfall days in December: 0.7 days

The month with the highest number of snowfall days is February (2.4 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).

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Average daylight in December /
Average sunshine in December
Hillsboro, OR

Average daylight in December / Average sunshine in December - Hillsboro, OR
  • Average daylight in December: 8h and 46min

The month with the longest days is June (Average daylight: 15h and 38min).
The month with the shortest days is December (Average daylight: 8h and 46min).

  • Average sunshine in December: 3h and 54min

The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 3h and 42min).

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Average sunshine days in December
Hillsboro, OR

Average sunshine days in December - Hillsboro, OR
  • Average sunshine days in December: 10.5 days

The month with the most sunshine days is July (24.4 days).
The month with the least sunshine days is March (8.5 days).

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Average UV index in December
Hillsboro, OR

Average UV index in December - Hillsboro, OR
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in December
Hillsboro, OR

Average cloud cover in December - Hillsboro, OR
  • Average cloud cover in December: 60

The month with the most cloud cover is February (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 25).

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Average visibility in December
Hillsboro, OR

Average visibility in December - Hillsboro, OR
  • Average visibility in December: 5mi

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

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