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May Weather in Philadelphia, United States

Last updated: June 24, 2025

In May, the average temperature in Philadelphia, United States hovers around 21°C (70°F). However, be prepared for a range, as temperatures can dip to a chilly 3°C (37°F) and soar to a warm 33°C (91°F). This month sees 113 mm (4.4 in) of precipitation spread over 12 days, complemented by an average humidity of 85%. Stay hydrated and enjoy the mix of warm days and refreshing showers!

May Temperature in Philadelphia

In May in Philadelphia, the average temperature is 21°C (70°F). Maximum temperatures can reach 33°C (91°F), while the minimum can drop to as low as 3°C (37°F). This makes Philadelphia an ideal destination for travelers seeking a pleasant climate with a range of temperatures suitable for various outdoor activities.

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

The chart illustrates May 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, May typically has an average temperature of 21°C (70°F), with highs reaching up to 33°C (91°F) and lows dropping to around 3°C (37°F).
JanFebMarAprMayJunJulAugSepOctNovDec424753607076807874645046
Data source: Temperature data for Philadelphia 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.

May Precipitation in Philadelphia

In Philadelphia in May, the precipitation amount is 113 mm (4.4 in) spread over 12 days.

May Precipitation Trends in Philadelphia

The chart displays monthly precipitation patterns in Philadelphia, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Philadelphia, May typically receives around 113 mm (4.4 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec1001761601411131071111199211879137
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Philadelphia

In Philadelphia in May, humidity is 85%. With an average temperature of 21°C (70°F), this humidity feels like a warm, heavy blanket enveloping you, making travel feel slightly stifling and requiring frequent breaks to refresh in the shade or near water.

May Average Humidity in Philadelphia

This chart illustrates the average monthly humidity levels in Philadelphia, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Philadelphia is approximately 85%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%86%82%85%85%83%76%76%80%88%88%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Philadelphia

In Philadelphia in May, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Philadelphia.

Maximum UV Index Levels in Philadelphia for May

The chart shows the monthly maximum UV Index (UVI) for Philadelphia in May, 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 May, the maximum UV index in Philadelphia typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36810111111109753
Data source: Philadelphia May 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 May 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 May’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 May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (42°F)99 mm (3.9 inches)86%moderate
February Weather8°C (47°F)176 mm (6.9 inches)86%high
March Weather12°C (53°F)160 mm (6.3 inches)86%very high
April Weather15°C (60°F)141 mm (5.5 inches)82%very high
May Weather21°C (70°F)113 mm (4.4 inches)85%extreme
June Weather24°C (76°F)107 mm (4.2 inches)85%extreme
July Weather26°C (80°F)111 mm (4.4 inches)83%extreme
August Weather26°C (78°F)119 mm (4.7 inches)76%very high
September Weather24°C (75°F)92 mm (3.6 inches)76%very high
October Weather18°C (65°F)118 mm (4.6 inches)80%high
November Weather10°C (50°F)79 mm (3.1 inches)88%moderate
December Weather8°C (46°F)137 mm (5.4 inches)88%moderate

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