Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
The month of December sees the lowest average temperatures, reaching 55.6°F (13.1°C) at the peak and 49.3°F (9.6°C) at the low.Humidity
The months with the lowest humidity in Half Moon Bay are November and December, with an average relative humidity of 72%.Rainfall
In Half Moon Bay, in December, during 8.4 rainfall days, 1.5" (38mm) of precipitation is typically accumulated. Throughout the year, there are 76.8 rainfall days, and 8.54" (217mm) of precipitation is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 36min of daylight.On the first day of December, sunrise is at 7:06 am and sunset at 4:51 pm. On the last day of the month, sunrise is at 7:24 am and sunset at 5:02 pm PST.
Sunshine
With an average of 5.7h of sunshine, December has the least sunshine of the year.UV index
The months with the lowest UV index are January through May, July, October through December, with an average maximum UV index of 4. A UV Index of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for average individuals.Note: The maximum UV index, 4 during December, leads to the following recommendations:
Act with care - The need to guard against sun damage is communicated. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. Using UVA and UVB-protective sunglasses and sun-protective clothing is effective against UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What time of the year is the coldest?
What are December temperatures?
What is the least humid month?
What is the average humidity in December?
How much does it rain in December?
What is the month with the shortest days?
What is the average length of the day in December?
What time are sunrise and sunset in December?
What is the month with the least sunshine?
How many hours of sunshine does Half Moon Bay have in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Half Moon Bay, CA
- Average high temperature in December: 55.6°F
The warmest month (with the highest average high temperature) is September (66.9°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in December: 49.3°F
The month with the highest average low temperature is September (56.7°F).
The coldest month (with the lowest average low temperature) is February (48.7°F).
Average pressure in December
Half Moon Bay, CA
- Average pressure in December: 30.1"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
Half Moon Bay, CA
- Average wind speed in December: 8.4mph
The windiest month (with the highest average wind speed) is April (9.6mph).
The calmest month (with the lowest average wind speed) is August (6.6mph).
Average humidity in December
Half Moon Bay, CA
- Average humidity in December: 72%
The month with the highest relative humidity is August (82%).
The months with the lowest relative humidity are November and December (72%).
Average rainfall in December
Half Moon Bay, CA
- Average rainfall in December: 1.5"
The wettest month (with the highest rainfall) is February (1.61").
The driest months (with the least rainfall) are June and July (0.12").
Average rainfall days in December
Half Moon Bay, CA
- Average rainfall days in December: 8.4 days
The month with the highest number of rainy days is March (10.8 days).
The month with the least rainy days is June (3 days).
Average daylight in December /
Average sunshine in December
Half Moon Bay, CA
- Average daylight in December: 9h and 4min
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 4min
The month with the most sunshine is July (Average sunshine: 11h and 24min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in December
Half Moon Bay, CA
- Average sunshine days in December: 21.1 days
The month with the most sunshine days is October (24.6 days).
The months with the least sunshine days are March and August (18.8 days).
Average UV index in December
Half Moon Bay, CA
- Average UV index in December: 4
The months with the highest UV index are June, August and September (UV index 5).
The months with the lowest UV index are January, February, March, April, May, July, October, November and December (UV index 4).
Average cloud cover in December
Half Moon Bay, CA
- Average cloud cover in December: 36
The month with the most cloud cover is March (Cloud cover 38).
The month with the least cloud cover is September (Cloud cover 18).
Average visibility in December
Half Moon Bay, 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).
Half Moon Bay, California, USA
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