December weather forecastSan Ysidro, CA
December
Weather in December
The first month of the winter, December, is still a comfortable month in San Ysidro, California, with an average temperature fluctuating between 64°F (17.8°C) and 50.4°F (10.2°C).Temperature
With average high temperatures of 64°F (17.8°C) and lows of 50.4°F (10.2°C), December is the coldest month.Humidity
The average relative humidity in December in San Ysidro is 59%.Rainfall
In San Ysidro, in December, it is raining for 6 days, with typically 1.26" (32mm) of accumulated precipitation. Throughout the year, there are 57.8 rainfall days, and 7.28" (185mm) of precipitation is accumulated.Daylight
The month with the shortest days is December, with an average of 10h and 6min of daylight.On the first day of the month, sunrise is at 6:32 am and sunset at 4:42 pm. On the last day of December, sunrise is at 6:49 am and sunset at 4:53 pm PST.
Sunshine
The month with the least sunshine is December, with an average of 6.6h of sunshine.UV index
January, February, 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 the ordinary person.Note: In December, the maximum UV index of 4 transforms into these recommendations:
Preventative actions are necessary - The mandate to avoid skin and eye damage is in place. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Tightly woven clothing, when worn loosely, shields effectively against the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
San Ysidro, CA
- Average high temperature in December: 64°F
The warmest month (with the highest average high temperature) is August (81.1°F).
The month with the lowest average high temperature is December (64°F).
- Average low temperature in December: 50.4°F
The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is February (50.2°F).
Average pressure in December
San Ysidro, CA
- Average pressure in December: 30.06"Hg
The month with the highest atmospheric pressure is January (30.08"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.88"Hg).
Average wind speed in December
San Ysidro, CA
- Average wind speed in December: 5.2mph
The windiest months (with the highest average wind speed) are April and May (6mph).
The calmest month (with the lowest average wind speed) is October (4.8mph).
Average humidity in December
San Ysidro, CA
- Average humidity in December: 59%
The month with the highest relative humidity is May (68%).
The month with the lowest relative humidity is November (55%).
Average rainfall in December
San Ysidro, CA
- Average rainfall in December: 1.26"
The wettest month (with the highest rainfall) is February (1.5").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in December
San Ysidro, CA
- Average rainfall days in December: 6 days
The month with the highest number of rainy days is March (7.5 days).
The month with the least rainy days is June (1.8 days).
Average daylight in December /
Average sunshine in December
San Ysidro, CA
- Average daylight in December: 10h and 6min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 6min).
- Average sunshine in December: 6h and 36min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).
Average sunshine days in December
San Ysidro, CA
- Average sunshine days in December: 23.5 days
The month with the most sunshine days is June (27.8 days).
The month with the least sunshine days is February (20.8 days).
Average UV index in December
San Ysidro, 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
San Ysidro, CA
- Average cloud cover in December: 25
The months with the most cloud cover are March and December (Cloud cover 25).
The month with the least cloud cover is August (Cloud cover 8).
Average visibility in December
San Ysidro, 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).
