December weather forecastHillsboro, OR
December
Weather in December
December brings the full force of winter to Hillsboro with an average high temperature of about 43.9°F (6.6°C) and an increase in rainfall to 4.45" (113mm) on average. The dwindling daylight hours, coupled with often cloudy skies and relatively high humidity, underline the chill factor. Subtle snowfall marks the festive season, lending a white veneer to the city, though instances are sparse. Despite the cold, the festive spirit permeates the cityscape, making it an exciting period in Hillsboro. Despite grey, short days, Hillsboro sparkles with holiday lights making winter sightseeing a unique experience.Temperature
The coldest time of the year is December, with temperatures averaging a high of 43.9°F (6.6°C) and a low of 34°F (1.1°C).Humidity
January, February, November and December, with an average relative humidity of 85%, are the most humid months.Rainfall
In Hillsboro, in December, it is raining for 18.8 days, with typically 4.45" (113mm) of accumulated precipitation. 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 are January through March, November and December. In Hillsboro, during December, snow falls for 0.7 days and regularly aggregates up to 0.35" (9mm) of snow. Throughout the year, there are 6.6 snowfall days, and 4.53" (115mm) of snow is accumulated.Daylight
With an average of 8h and 48min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 7:32 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 December, the average sunshine 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 in Hillsboro. 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: In December, the maximum UV index of 2 suggests these recommendations:
Despite the majority tolerating prolonged sun exposure, those with sensitive skin, infants, and children demand continual protection. The solar radiation around mid-day is intense; avoid the Sun and stay safe. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Be prepared! The intensity of the Sun's UV radiation can be amplified nearly double due to snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
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).
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).
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).
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%).
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").
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).
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").
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).
Average daylight in December /
Average sunshine in December
Hillsboro, OR
- Average daylight in December: 8h and 48min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- 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).
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).
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).
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).
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).
