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January Weather in San Diego, United States

Last updated: June 24, 2025

The average temperature in San Diego, United States during January is a comfortable 14°C (58°F). However, be prepared for a temperature range that can swing from a chilly -5°C (24°F) to a warm 34°C (94°F). During this month, expect about 27 mm (1.1 in) of precipitation over 5 days, with an average humidity level of 83%.

January Temperature in San Diego

In January in San Diego, the average temperature is 14°C (58°F). Maximum temperatures can reach up to 34°C (94°F), while the minimum can drop as low as -5°C (24°F). Therefore, it’s essential to pack a variety of clothing to accommodate both warm and chilly conditions while exploring.

January Weather in San Diego: Daily Temperature Highs, Lows, and Averages

The chart illustrates January temperature patterns in San Diego, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Diego, January typically has an average temperature of 14°C (58°F), with highs reaching up to 34°C (94°F) and lows dropping to around -5°C (24°F).
JanFebMarAprMayJunJulAugSepOctNovDec586169748184858682756661
Data source: Temperature data for San Diego generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

January Precipitation in San Diego

In San Diego in January, the precipitation amount is 27 mm (1.1 in) over a period of 5 days.

January Precipitation Trends in San Diego

The chart displays monthly precipitation patterns in San Diego, with values for each month alongside January’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how January’s conditions compare to those of other months. In San Diego, January typically receives around 27 mm (1.1 inches) of precipitation spread over approximately 5 days.
JanFebMarAprMayJunJulAugSepOctNovDec2724544199887952104443738
Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.
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January Humidity in San Diego

In San Diego in January, humidity is 83%. With an average temperature of 14°C (58°F), this humidity feels like a thick blanket enveloping you, making exploration feel heavier and sweatier, so be prepared for a slower pace while traveling.

January Average Humidity in San Diego

This chart illustrates the average monthly humidity levels in San Diego, with January’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In January, average humidity in San Diego is approximately 83%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%79%76%77%80%73%66%65%73%76%80%86%
Data source: Humidity data for January generated using information from the Copernicus Climate Change Service.

January UV Index in San Diego

In San Diego in January, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in San Diego, you can refer to this Hourly UV Index in San Diego.

Maximum UV Index Levels in San Diego for January

The chart shows the monthly maximum UV Index (UVI) for San Diego in January, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In January, the maximum UV index in San Diego typically reaches 6, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec6810111112121211975
Data source: San Diego January UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How January Weather in San Diego Compares to Other Months

Weather in San Diego varies notably across the year, with each month offering distinct climate conditions. This page compares January’s weather to other months in San Diego, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in San Diego, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather14°C (58°F)27 mm (1.1 inches)83%high
February Weather16°C (61°F)24 mm (1.0 inches)79%very high
March Weather21°C (69°F)54 mm (2.1 inches)76%very high
April Weather24°C (75°F)41 mm (1.6 inches)77%extreme
May Weather27°C (81°F)99 mm (3.9 inches)80%extreme
June Weather29°C (84°F)88 mm (3.4 inches)73%extreme
July Weather30°C (86°F)79 mm (3.1 inches)66%extreme
August Weather30°C (87°F)52 mm (2.1 inches)65%extreme
September Weather28°C (82°F)104 mm (4.1 inches)73%extreme
October Weather24°C (76°F)44 mm (1.7 inches)76%very high
November Weather19°C (66°F)37 mm (1.4 inches)80%high
December Weather16°C (61°F)38 mm (1.5 inches)86%moderate

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