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
December is the month when South San Francisco experiences its coldest temperatures, averaging a high of 55.6°F (13.1°C) and a low of 47.8°F (8.8°C).Humidity
The average relative humidity in December is 72%.Rainfall
In South San Francisco, during December, the rain falls for 7.7 days and regularly aggregates up to 0.71" (18mm) of precipitation. In South San Francisco, during the entire year, the rain falls for 53.6 days and collects up to 3.9" (99mm) of precipitation.Daylight
The month with the shortest days is December, 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 in South San Francisco is December, with an average of 5.8h of sunshine.UV index
The months with the lowest UV index are February and December, with an average maximum UV index of 3. A UV Index estimate of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.Note: The daily high UV index of 3 during December translates into the following recommendations:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. For skin protection, it's recommended to minimize Sun exposure during its peak hours around midday. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the coldest months?
What is the usual temperature for South San Francisco in December?
What is the average humidity in December?
How many days does it rain in December?
What is the month with the shortest days?
What is the average length of the day in December?
When are sunrise and sunset in December?
What is the month with the least sunshine?
How long on average sun shines in December?
When is the lowest UV index?
What is the UV index reading in December?
Average temperature in December
South San Francisco, CA
- Average high temperature in December: 55.6°F
The warmest month (with the highest average high temperature) is September (70°F).
The month with the lowest average high temperature is December (55.6°F).
- Average low temperature in December: 47.8°F
The months with the highest average low temperature are August and September (56.5°F).
The coldest months (with the lowest average low temperature) are January, February and December (47.8°F).
Average pressure in December
South San Francisco, 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
South San Francisco, CA
- Average wind speed in December: 7.3mph
The windiest month (with the highest average wind speed) is April (8.5mph).
The calmest month (with the lowest average wind speed) is September (6.2mph).
Average humidity in December
South San Francisco, CA
- Average humidity in December: 72%
The month with the highest relative humidity is August (78%).
The months with the lowest relative humidity are October and November (71%).
Average rainfall in December
South San Francisco, CA
- Average rainfall in December: 0.71"
The wettest month (with the highest rainfall) is February (0.79").
The driest months (with the least rainfall) are June, July and August (0.04").
Average rainfall days in December
South San Francisco, CA
- Average rainfall days in December: 7.7 days
The month with the highest number of rainy days is March (9.4 days).
The month with the least rainy days is June (1.1 days).
Average daylight in December /
Average sunshine in December
South San Francisco, 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 5min
The month with the most sunshine is July (Average sunshine: 11h and 42min).
The month with the least sunshine is December (Average sunshine: 5h and 48min).
Average sunshine days in December
South San Francisco, CA
- Average sunshine days in December: 22.2 days
The months with the most sunshine days are June, July and September (26.3 days).
The month with the least sunshine days is March (19.4 days).
Average UV index in December
South San Francisco, 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
South San Francisco, CA
- Average cloud cover in December: 35
The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is September (Cloud cover 16).
Average visibility in December
South San Francisco, 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).
South San Francisco, California, USA
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