January Weather in Petaluma, United States

Last updated: June 24, 2025

In January, the average temperature in Petaluma, United States hovers around 10°C (50°F), showcasing a climate that can vary significantly. Expect minimums dipping to -1°C (30°F) and maximums reaching up to 23°C (74°F). Rainfall is not uncommon, with 131 mm (5.2 in) expected over approximately 9 days. Additionally, the average humidity stands at a noteworthy 86%, contributing to the region's distinctive atmosphere.

January Temperature in Petaluma

In January in Petaluma, the average temperature is 10°C (50°F). Maximums can reach 23°C (74°F), and minimums can be as low as -1°C (30°F). Be prepared for a range of weather conditions if you're planning to travel during this month.

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

The chart illustrates January temperature patterns in Petaluma, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Petaluma, January typically has an average temperature of 10°C (50°F), with highs reaching up to 23°C (74°F) and lows dropping to around -1°C (30°F).

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

January Precipitation in Petaluma

In Petaluma in January, the precipitation amount is 131 mm (5.2 in) over the course of 9 days.

January Precipitation Trends in Petaluma

The chart displays monthly precipitation patterns in Petaluma, 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 Petaluma, January typically receives around 131 mm (5.2 inches) of precipitation spread over approximately 9 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 Petaluma

In Petaluma in January humidity is 86%. With an average temperature of 10°C (50°F), this humidity feels like a heavy blanket wrapping around you, making outdoor activities uncomfortable and sticky, which can dampen the spirit of travel.

January Average Humidity in Petaluma

This chart illustrates the average monthly humidity levels in Petaluma, 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 Petaluma is approximately 86%, 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 Petaluma

In Petaluma 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 Petaluma, you can check the information here.

Maximum UV Index Levels in Petaluma for January

The chart shows the monthly maximum UV Index (UVI) for Petaluma 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 Petaluma typically reaches 3, which falls under the moderate exposure category.

Data source: Petaluma 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 Petaluma Compares to Other Months

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

This table compares monthly weather conditions in Petaluma, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	10°C (50°F)	131 mm (5.2 inches)	86%	moderate
February Weather	10°C (51°F)	147 mm (5.8 inches)	84%	moderate
March Weather	11°C (52°F)	93 mm (3.7 inches)	83%	high
April Weather	13°C (56°F)	45 mm (1.8 inches)	80%	very high
May Weather	15°C (60°F)	27 mm (1.0 inches)	80%	very high
June Weather	18°C (65°F)	2 mm (0.1 inches)	76%	extreme
July Weather	18°C (65°F)	1 mm (0.0 inches)	70%	extreme
August Weather	18°C (65°F)	1 mm (0.0 inches)	66%	very high
September Weather	18°C (65°F)	2 mm (0.1 inches)	68%	very high
October Weather	16°C (61°F)	38 mm (1.5 inches)	72%	high
November Weather	12°C (54°F)	59 mm (2.3 inches)	84%	moderate
December Weather	9°C (49°F)	103 mm (4.1 inches)	84%	moderate