San Diego
California, USA
Long-term weather forecast
Long-term weather forecast

January weather forecast and climate
San Diego, CA

The view of Coronado Island in San Diego, California, from across a water body on a sidewalk, with a row of palm trees
The view of Coronado Island in San Diego, California, from across a water body on a sidewalk, with a row of palm trees
January, like December, in San Diego, California, is another comfortable winter month, with average temperature ranging between min 52.7°F (11.5°C) and max 64.2°F (17.9°C).

Temperature

In January, the average high-temperature is relatively the same as in December - a still comfortable 64.2°F (17.9°C). In January, in San Diego, the average low-temperature is 52.7°F (11.5°C).

Humidity

The average relative humidity in San Diego, California, is 60%.

Rainfall

In San Diego, it is raining for 5.3 days, with typically 1.06" (27mm) of accumulated precipitation. Throughout the year, in San Diego, there are 61.8 rainfall days, and 8.7" (221mm) of precipitation is accumulated.

Ocean temperature

In San Diego, California, the average water temperature is 59.4°F (15.2°C).
Note: For swimming, a surface water temperature of 59.4°F (15.2°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

Daylight

In San Diego, the average length of the day in January is 10.3h.

Sunshine

The average sunshine in San Diego is 6.8h.

UV index

Months with the lowest UV index in San Diego are January through March, November and December, with an average maximum UV index of 4. A UV Index reading of 3 to 5 represents a medium vulnerability from the exposure to the Sun's UV rays for average individuals.
Note: The daily maximum UV index of 4 interpret into the following advice:
Take precautions - Protection against sun damage is advised. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.

What is the temperature in January in San Diego?

In San Diego, California, in January, the average high-temperature is 64.2°F (17.9°C), and the average low-temperature is 52.7°F (11.5°C).

What is the average humidity in January in San Diego?

The average relative humidity in January is 60%.

How many days does it rain in January in San Diego?

In San Diego, during January, the rain falls for 5.3 days and regularly aggregates up to 1.06" (27mm) of precipitation.

What is the ocean temperature in January in San Diego?

In San Diego, in January, the average water temperature is 59.4°F (15.2°C). For most, swimming in 59.4°F (15.2°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).

How many hours of daylight does San Diego have in January?

In January, the average length of the day in San Diego, California, is 10.3h.

How long on average sun shines in January in San Diego?

In San Diego, the average sunshine in January is 6.8h.

What is the month with the lowest UV index in San Diego?

January through March, November and December, with an average maximum UV index of 4, are months with the lowest UV index in San Diego.

How high is the UV index in January in San Diego?

The average daily maximum UV index in January in San Diego is 4. A UV Index reading of 3 to 5 represents a medium hazard to health from unsafe exposure to the Sun's UV rays.
Average temperature in January - San Diego, CA
  • Average high temperature in January: 64.2°F

The warmest month (with the highest average high temperature) is August (77.4°F).
The month with the lowest average high temperature is February (63.1°F).

  • Average low temperature in January: 52.7°F

The month with the highest average low temperature is August (65.7°F).
The coldest month (with the lowest average low temperature) is February (51.8°F).

Average humidity in January - San Diego, CA
  • Average humidity in January: 60%

The month with the highest relative humidity is June (73%).
The month with the lowest relative humidity is November (59%).

Average rainfall in January - San Diego, CA
  • Average rainfall in January: 1.06"

The wettest month (with the highest rainfall) is December (1.65").
The driest month (with the lowest rainfall) is June (0.12").

Average rainfall days in January - San Diego, CA
  • Average rainfall days in January: 5.3 days

The month with the highest number of rainy days is March (7.6 days).
The month with the lowest number of rainy days is June (2.7 days).

Average sea temperature in January - San Diego, CA
  • Average sea temperature in January: 59.2°F

The best month for swimming (with the highest average sea temperature) is August (67.9°F).
The coldest month (with the lowest average sea temperature) is February (58.7°F).

Average daylight in January / Average sunshine in January - San Diego, CA
  • Average daylight in January: 10.3h

The month with the longest days is June (Average daylight: 14.3h).
The month with shortest days is December (Average daylight: 10h).

  • Average sunshine in January: 6.8h

Months with most sunshine are July and August (Average sunshine: 11.9h).
The month with least sunshine is December (Average sunshine: 6.7h).

Average UV index in January - San Diego, CA
  • Average UV index in January: 4

Months with the highest UV index are July, August and September (UV index 6).
Months with the lowest UV index are January, February, March, November and December (UV index 4).