nomadseason

January Weather in California, United States

Last updated: June 24, 2025

In California, United States, the average temperature in January is a chilly 0°C (33°F), where the mercury can dip to a brisk -21°C (-6°F) at its lowest and rise to a mild 19°C (67°F) at its highest. Expect about 68 mm (2.7 in) of precipitation spread over 6 days, along with an average humidity of 80%, making this month a characteristically damp and cool period.

January Temperature in California

In January in California, the average temperature is 0°C (33°F). The maximum can reach 19°C (67°F), and the minimum can be as low as -21°C (-6°F). Be prepared for a wide range of temperatures if you plan to travel during this time.

January Weather in California: Daily Temperature Highs, Lows, and Averages

The chart illustrates January temperature patterns in California, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In California, January typically has an average temperature of 0°C (33°F), with highs reaching up to 19°C (67°F) and lows dropping to around -21°C (-6°F).
JanFebMarAprMayJunJulAugSepOctNovDec323547546676807672584539
Data source: Temperature data for California generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

January Precipitation in California

In California in January, the precipitation amount is 68 mm (2.7 in) spread over the course of 6 days.

January Precipitation Trends in California

The chart displays monthly precipitation patterns in California, 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 California, January typically receives around 68 mm (2.7 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec6860114124176113115106611075638
Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

January Humidity in California

In California in January humidity is 80%. With an average temperature of 0°C (33°F), this humidity feels like an uncomfortable chill that clings to your skin, making travel feel damp and frigid, as if each breath is infused with brisk moisture that can seep through your layers.

January Average Humidity in California

This chart illustrates the average monthly humidity levels in California, 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 California is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec80%78%75%77%82%83%81%78%72%72%84%86%
Data source: Humidity data for January generated using information from the Copernicus Climate Change Service.

January UV Index in California

In California in January, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in California, you can check the information here.

Maximum UV Index Levels in California for January

The chart shows the monthly maximum UV Index (UVI) for California 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 California typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101111109743
Data source: California 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 California Compares to Other Months

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

This table compares monthly weather conditions in California, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)68 mm (2.7 inches)80%moderate
February Weather1°C (35°F)60 mm (2.4 inches)78%moderate
March Weather8°C (47°F)114 mm (4.5 inches)75%high
April Weather12°C (55°F)124 mm (4.9 inches)77%very high
May Weather19°C (67°F)175 mm (6.9 inches)82%very high
June Weather25°C (77°F)113 mm (4.4 inches)83%extreme
July Weather26°C (80°F)115 mm (4.5 inches)81%extreme
August Weather25°C (77°F)106 mm (4.2 inches)78%very high
September Weather22°C (73°F)61 mm (2.4 inches)72%very high
October Weather14°C (58°F)107 mm (4.2 inches)72%high
November Weather7°C (45°F)56 mm (2.2 inches)84%moderate
December Weather4°C (39°F)38 mm (1.5 inches)86%moderate

Compare California's Climate with Cities Worldwide