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January Weather in Santa Rosa, United States

Last updated: June 24, 2025

In January, the average temperature in Santa Rosa, United States hovers around 4°C (39°F). Expect a chilly stretch, with minimums plunging to -25°C (-13°F) and maximums reaching up to 20°C (69°F). During this time, you can anticipate approximately 15 mm (0.6 in) of precipitation over 3 days and an average humidity level of 74%, creating a brisk yet dynamic atmosphere.

January Temperature in Santa Rosa

In January in Santa Rosa, the average temperature is 4°C (39°F). Maximums can reach up to 20°C (69°F), while minimums can plummet to as low as -25°C (-13°F). Be prepared for a wide range of temperatures during your travels, so pack accordingly!

January Weather in Santa Rosa: Daily Temperature Highs, Lows, and Averages

The chart illustrates January temperature patterns in Santa Rosa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Santa Rosa, January typically has an average temperature of 4°C (39°F), with highs reaching up to 20°C (69°F) and lows dropping to around -25°C (-13°F).
JanFebMarAprMayJunJulAugSepOctNovDec394251586877797772584941
Data source: Temperature data for Santa Rosa 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 Santa Rosa

In Santa Rosa in January, the precipitation amount is 15 mm (0.6 in) over the course of 3 days.

January Precipitation Trends in Santa Rosa

The chart displays monthly precipitation patterns in Santa Rosa, 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 Santa Rosa, January typically receives around 15 mm (0.6 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec151228273041315633481411
Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.
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January Humidity in Santa Rosa

In Santa Rosa in January humidity is 74%. With an average temperature of 4°C (39°F), this humidity feels like a damp chill that seeps into your bones, making traveling uncomfortable and necessitating extra layers to stay warm while navigating the potentially slippery streets.

January Average Humidity in Santa Rosa

This chart illustrates the average monthly humidity levels in Santa Rosa, 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 Santa Rosa is approximately 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec74%75%61%62%69%74%75%78%76%76%80%77%
Data source: Humidity data for January generated using information from the Copernicus Climate Change Service.

January UV Index in Santa Rosa

In Santa Rosa in January, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Santa Rosa for better planning.

Maximum UV Index Levels in Santa Rosa for January

The chart shows the monthly maximum UV Index (UVI) for Santa Rosa 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 Santa Rosa typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec479111213121211854
Data source: Santa Rosa 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 Santa Rosa Compares to Other Months

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

This table compares monthly weather conditions in Santa Rosa, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather4°C (39°F)15 mm (0.6 inches)74%moderate
February Weather6°C (43°F)12 mm (0.5 inches)75%high
March Weather11°C (51°F)28 mm (1.1 inches)61%very high
April Weather14°C (58°F)27 mm (1.1 inches)61%extreme
May Weather20°C (68°F)30 mm (1.2 inches)69%extreme
June Weather25°C (78°F)41 mm (1.6 inches)74%extreme
July Weather26°C (80°F)31 mm (1.2 inches)75%extreme
August Weather25°C (77°F)56 mm (2.2 inches)78%extreme
September Weather22°C (72°F)33 mm (1.3 inches)76%extreme
October Weather14°C (58°F)47 mm (1.9 inches)76%very high
November Weather9°C (49°F)14 mm (0.6 inches)80%moderate
December Weather5°C (42°F)11 mm (0.4 inches)77%moderate

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