January Weather in Philadelphia, United States

Last updated: June 24, 2025

In Philadelphia, United States, the average temperature in January is a cool 6°C (42°F), with temperatures ranging from a chilly -12°C (10°F) to a mild 23°C (73°F). Expect 99 mm (3.9 in) of precipitation spread over 11 days, contributing to an average humidity of around 86%. Prepare for a mix of brisk air and wet days!

January Temperature in Philadelphia

In January in Philadelphia, the average temperature is 6°C (42°F). Maximums can reach 23°C (73°F) and minimums can drop as low as -12°C (10°F). Be prepared for a wide range of temperatures if you're planning to visit during this time!

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

The chart illustrates January temperature patterns in Philadelphia, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Philadelphia, January typically has an average temperature of 6°C (42°F), with highs reaching up to 23°C (73°F) and lows dropping to around -12°C (10°F).

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

January Precipitation in Philadelphia

In Philadelphia, in January, the precipitation amount is 99 mm (3.9 in) over the course of 11 days.

January Precipitation Trends in Philadelphia

The chart displays monthly precipitation patterns in Philadelphia, 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 Philadelphia, January typically receives around 99 mm (3.9 inches) of precipitation spread over approximately 11 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 Philadelphia

In Philadelphia in January, humidity is 86%. With an average temperature of 6°C (42°F), this humidity feels like a chilly, damp embrace that can make outdoor activities feel uncomfortable and chilly, prompting travelers to seek shelter or warm clothing to stay cozy while exploring.

January Average Humidity in Philadelphia

This chart illustrates the average monthly humidity levels in Philadelphia, 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 Philadelphia 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 Philadelphia

In Philadelphia 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 Philadelphia, you can check the information here.

Maximum UV Index Levels in Philadelphia for January

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

Data source: Philadelphia 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 Philadelphia Compares to Other Months

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

This table compares monthly weather conditions in Philadelphia, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	6°C (42°F)	99 mm (3.9 inches)	86%	moderate
February Weather	8°C (47°F)	176 mm (6.9 inches)	86%	high
March Weather	12°C (53°F)	160 mm (6.3 inches)	86%	very high
April Weather	15°C (60°F)	141 mm (5.5 inches)	82%	very high
May Weather	21°C (70°F)	113 mm (4.4 inches)	85%	extreme
June Weather	24°C (76°F)	107 mm (4.2 inches)	85%	extreme
July Weather	26°C (80°F)	111 mm (4.4 inches)	83%	extreme
August Weather	26°C (78°F)	119 mm (4.7 inches)	76%	very high
September Weather	24°C (75°F)	92 mm (3.6 inches)	76%	very high
October Weather	18°C (65°F)	118 mm (4.6 inches)	80%	high
November Weather	10°C (50°F)	79 mm (3.1 inches)	88%	moderate
December Weather	8°C (46°F)	137 mm (5.4 inches)	88%	moderate