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May Weather in Saint Charles, United States

Last updated: June 24, 2025

In May, the average temperature in Saint Charles, United States hovers around 17°C (63°F). Expect a wide range, with minimums dropping to 1°C (34°F) and maximums soaring up to 37°C (99°F). The region experiences a precipitation total of 163 mm (6.4 in) over about 16 days, contributing to an average humidity level of 77%.

May Temperature in Saint Charles

In May in Saint Charles, the average temperature is 17°C (63°F), with maximums reaching 37°C (99°F) and minimums dropping as low as 1°C (34°F). This makes it a versatile time for travelers, offering both warm and cooler conditions to suit various outdoor activities.

May Weather in Saint Charles: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Saint Charles, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint Charles, May typically has an average temperature of 17°C (63°F), with highs reaching up to 37°C (99°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec232540506375787469533932
Data source: Temperature data for Saint Charles 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 Saint Charles

In Saint Charles in May, the precipitation amount is 163 mm (6.4 in) spread out over 16 days.

May Precipitation Trends in Saint Charles

The chart displays monthly precipitation patterns in Saint Charles, 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 Saint Charles, May typically receives around 163 mm (6.4 inches) of precipitation spread over approximately 16 days.
JanFebMarAprMayJunJulAugSepOctNovDec4139856916311769761171344336
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Saint Charles

In Saint Charles in May, humidity is 77%. With an average temperature of 17°C (63°F), this humidity feels like a cozy blanket wrapped around you, creating a muggy atmosphere that can be a bit uncomfortable for traveling, making you want to seek shade and hydration as you explore.

May Average Humidity in Saint Charles

This chart illustrates the average monthly humidity levels in Saint Charles, 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 Saint Charles is approximately 77%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec78%80%77%78%77%81%81%77%73%75%85%83%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Saint Charles

In Saint Charles in May, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Saint Charles.

Maximum UV Index Levels in Saint Charles for May

The chart shows the monthly maximum UV Index (UVI) for Saint Charles 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 Saint Charles typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec35689111098643
Data source: Saint Charles 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 Saint Charles Compares to Other Months

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

This table compares monthly weather conditions in Saint Charles, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)41 mm (1.6 inches)78%moderate
February Weather-4°C (25°F)39 mm (1.6 inches)80%moderate
March Weather5°C (41°F)85 mm (3.3 inches)77%high
April Weather10°C (50°F)69 mm (2.7 inches)77%very high
May Weather17°C (63°F)163 mm (6.4 inches)77%very high
June Weather24°C (75°F)117 mm (4.6 inches)81%extreme
July Weather25°C (78°F)69 mm (2.7 inches)81%very high
August Weather24°C (75°F)76 mm (3.0 inches)77%very high
September Weather20°C (69°F)117 mm (4.6 inches)73%very high
October Weather12°C (53°F)134 mm (5.3 inches)75%high
November Weather4°C (39°F)43 mm (1.7 inches)85%moderate
December Weather0°C (32°F)36 mm (1.4 inches)83%moderate

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