December weather forecastCosta Mesa, CA
December
Weather in December
December, the first month of the winter in Costa Mesa, is also an enjoyable month, with an average temperature fluctuating between 53.1°F (11.7°C) and 62.4°F (16.9°C).Temperature
The lowest temperatures are recorded in December, with averages reaching a high of 62.4°F (16.9°C) and a low of 53.1°F (11.7°C).Humidity
The average relative humidity in December in Costa Mesa is 61%.Rainfall
The month with the most rainfall is December, when the rain falls for 6.2 days and typically aggregates up to 0.79" (20mm) of precipitation.Daylight
The month with the shortest days is December, with an average of 10h and 0min of daylight.On the first day of December, sunrise is at 6:38 am and sunset at 4:43 pm. On the last day of the month, sunrise is at 6:56 am and sunset at 4:54 pm PST.
Sunshine
With an average of 6.6h of sunshine, December has the least sunshine of the year in Costa Mesa.UV index
January through March, November and December, with an average maximum UV index of 4, are months with the lowest UV index. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for average individuals.Note: An average UV index of 4 in December transforms into this advice:
Be vigilant - A duty to shield skin and eyes from injury exists. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Costa Mesa, CA
- Average high temperature in December: 62.4°F
The warmest month (with the highest average high temperature) is August (76.6°F).
The month with the lowest average high temperature is December (62.4°F).
- Average low temperature in December: 53.1°F
The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is February (52.3°F).
Average pressure in December
Costa Mesa, CA
- Average pressure in December: 30.07"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are June and September (29.89"Hg).
Average wind speed in December
Costa Mesa, CA
- Average wind speed in December: 5.7mph
The windiest month (with the highest average wind speed) is April (6.6mph).
The calmest month (with the lowest average wind speed) is October (5.2mph).
Average humidity in December
Costa Mesa, CA
- Average humidity in December: 61%
The month with the highest relative humidity is June (74%).
The month with the lowest relative humidity is November (59%).
Average rainfall in December
Costa Mesa, CA
- Average rainfall in December: 0.79"
The wettest month (with the highest rainfall) is December (0.79").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in December
Costa Mesa, CA
- Average rainfall days in December: 6.2 days
The month with the highest number of rainy days is March (6.6 days).
The month with the least rainy days is June (1.6 days).
Average daylight in December /
Average sunshine in December
Costa Mesa, CA
- Average daylight in December: 10h and 0min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in December: 6h and 36min
The month with the most sunshine is August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).
Average sunshine days in December
Costa Mesa, CA
- Average sunshine days in December: 23.6 days
The month with the most sunshine days is June (26.5 days).
The month with the least sunshine days is February (20.5 days).
Average UV index in December
Costa Mesa, CA
- Average UV index in December: 4
The months with the highest UV index are July, August and September (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 4).
Average cloud cover in December
Costa Mesa, CA
- Average cloud cover in December: 24
The months with the most cloud cover are March and December (Cloud cover 24).
The month with the least cloud cover is August (Cloud cover 8).
Average visibility in December
Costa Mesa, 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).
