January Weather in California, United States

Last updated: June 24, 2025

In California, United States during January, the average temperature hovers around 0°C (33°F). You might experience a chill, with minimum temperatures plunging to -23°C (-10°F), while on warmer days, the mercury can rise to a pleasant 22°C (72°F). Expect precipitation of about 87 mm (3.4 in) over 12 days, and be prepared for a fairly high humidity level of 88%.

January Temperature in California

In January in California, the average temperature is 0°C (33°F). Maximum temperatures can reach 22°C (72°F), while minimums can drop as low as -23°C (-10°F). Be prepared for a wide range of weather conditions when traveling during this month.

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 22°C (72°F) and lows dropping to around -23°C (-10°F).

Data source: Temperature data for California generated using information from the Copernicus Climate Change Service.

January Precipitation in California

In California in January, the precipitation amount is 87 mm (3.4 in) over the course of 12 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 87 mm (3.4 inches) of precipitation spread over approximately 12 days.

Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

January Humidity in California

In California in January, humidity is 88%. With an average temperature of 0°C (33°F), this humidity feels like a damp chill that seeps into your bones, making travel uncomfortable and requiring extra layers to stay warm and dry.

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 88%, offering insight into how humid the weather typically is during this month.

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.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	0°C (33°F)	87 mm (3.4 inches)	88%	moderate
February Weather	2°C (37°F)	124 mm (4.9 inches)	88%	moderate
March Weather	6°C (43°F)	117 mm (4.6 inches)	88%	high
April Weather	11°C (53°F)	129 mm (5.1 inches)	86%	very high
May Weather	17°C (63°F)	149 mm (5.9 inches)	82%	very high
June Weather	21°C (70°F)	172 mm (6.8 inches)	84%	very high
July Weather	24°C (75°F)	153 mm (6.0 inches)	82%	very high
August Weather	23°C (73°F)	110 mm (4.3 inches)	73%	very high
September Weather	20°C (68°F)	125 mm (4.9 inches)	73%	very high
October Weather	14°C (58°F)	121 mm (4.8 inches)	81%	high
November Weather	6°C (43°F)	86 mm (3.4 inches)	89%	moderate
December Weather	3°C (38°F)	116 mm (4.6 inches)	86%	moderate