December weather forecastWestmont, CA
December
Weather in December
The first month of the winter, December, is still a comfortable month in Westmont, California, with an average temperature fluctuating between 64°F (17.8°C) and 51.4°F (10.8°C).Temperature
December stands out as Westmont's coldest month, with an average high-temperature of 64°F (17.8°C) and a low-temperature of 51.4°F (10.8°C).Humidity
In December, the average relative humidity is 56%.Rainfall
In December, the rain falls for 5 days. Throughout December, 1.3" (33mm) of precipitation is accumulated. In Westmont, during the entire year, the rain falls for 47.6 days and collects up to 7.24" (184mm) of precipitation.Daylight
The month with the shortest days is December, with an average of 9h and 54min of daylight.On the first day of the month, sunrise is at 6:40 am and sunset at 4:44 pm. On the last day of December, sunrise is at 6:58 am and sunset at 4:54 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 6.7h of sunshine.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for average individuals.Note: The daily high UV index of 4 during December translates into the following recommendations:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Westmont, CA
- Average high temperature in December: 64°F
The warmest month (with the highest average high temperature) is August (80.2°F).
The month with the lowest average high temperature is December (64°F).
- Average low temperature in December: 51.4°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 (51.1°F).
Average pressure in December
Westmont, CA
- Average pressure in December: 30.07"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in December
Westmont, CA
- Average wind speed in December: 5.5mph
The windiest month (with the highest average wind speed) is April (6.4mph).
The calmest month (with the lowest average wind speed) is September (4.9mph).
Average humidity in December
Westmont, CA
- Average humidity in December: 56%
The month with the highest relative humidity is June (70%).
The month with the lowest relative humidity is November (54%).
Average rainfall in December
Westmont, CA
- Average rainfall in December: 1.3"
The wettest month (with the highest rainfall) is January (1.42").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in December
Westmont, CA
- Average rainfall days in December: 5 days
The month with the highest number of rainy days is March (6.5 days).
The month with the least rainy days is June (1.7 days).
Average daylight in December /
Average sunshine in December
Westmont, CA
- Average daylight in December: 9h and 54min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in December: 6h and 42min
The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in December
Westmont, CA
- Average sunshine days in December: 24.8 days
The month with the most sunshine days is October (25.5 days).
The month with the least sunshine days is June (21.4 days).
Average UV index in December
Westmont, CA
- Average UV index in December: 4
The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 4).
Average cloud cover in December
Westmont, CA
- Average cloud cover in December: 22
The months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 7).
Average visibility in December
Westmont, 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).
