December weather forecastHillsborough, CA
December
Weather in December
The first month of the winter, December, is also a moderate month in Hillsborough, California, with an average temperature varying between 47.8°F (8.8°C) and 55.6°F (13.1°C).Temperature
Hillsborough experiences its lowest average temperatures in December, reaching a peak of 55.6°F (13.1°C) and a minimum of 47.8°F (8.8°C).Humidity
The average relative humidity in December is 72%.Rainfall
In December, the rain falls for 11.1 days. Throughout December, 2.17" (55mm) of precipitation is accumulated. In Hillsborough, during the entire year, the rain falls for 81.5 days and collects up to 12.8" (325mm) of precipitation.Daylight
December has the shortest days of the year in Hillsborough, with an average of 9h and 36min of daylight.On the first day of the month, sunrise is at 7:06 am and sunset at 4:51 pm. On the last day of December, sunrise is at 7:24 am and sunset at 5:01 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 5.8h of sunshine.UV index
February and December, with an average maximum UV index of 3, are months with the lowest UV index. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for the average person.Note: In December, an average UV index of 3 transforms into the following instructions:
Adopt protective measures - Suggestions to resist sunburn are offered. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Hillsborough, CA
- Average high temperature in December: 55.6°F
The warmest month (with the highest average high temperature) is September (70.2°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in December: 47.8°F
The month with the highest average low temperature is September (56.8°F).
The coldest month (with the lowest average low temperature) is January (47.5°F).
Average pressure in December
Hillsborough, CA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.92"Hg).
Average wind speed in December
Hillsborough, CA
- Average wind speed in December: 7.2mph
The windiest month (with the highest average wind speed) is April (8.3mph).
The calmest month (with the lowest average wind speed) is September (6.1mph).
Average humidity in December
Hillsborough, CA
- Average humidity in December: 72%
The month with the highest relative humidity is August (78%).
The month with the lowest relative humidity is October (70%).
Average rainfall in December
Hillsborough, CA
- Average rainfall in December: 2.17"
The wettest month (with the highest rainfall) is February (2.44").
The driest month (with the least rainfall) is July (0.08").
Average rainfall days in December
Hillsborough, CA
- Average rainfall days in December: 11.1 days
The month with the highest number of rainy days is March (12.8 days).
The months with the least rainy days are June and July (2.4 days).
Average daylight in December /
Average sunshine in December
Hillsborough, CA
- Average daylight in December: 9h and 36min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in December: 5h and 48min
The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in December
Hillsborough, CA
- Average sunshine days in December: 19.1 days
The month with the most sunshine days is July (24.6 days).
The month with the least sunshine days is March (16.3 days).
Average UV index in December
Hillsborough, CA
- Average UV index in December: 3
The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February and December (UV index 3).
Average cloud cover in December
Hillsborough, CA
- Average cloud cover in December: 35
The month with the most cloud cover is March (Cloud cover 36).
The months with the least cloud cover are July and September (Cloud cover 15).
Average visibility in December
Hillsborough, CA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
