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August Weather in Saint Charles, United States

Last updated: June 24, 2025

In Saint Charles, United States, the average temperature in August hovers around 24°C (75°F), creating a pleasant atmosphere for visitors. Temperatures can vary significantly, with a minimum of 11°C (52°F) and a maximum of 36°C (97°F). During this time, expect approximately 76 mm (3.0 in) of precipitation spread across 8 days, and enjoy the lush air with an average humidity of 77%.

August Temperature in Saint Charles

In August in Saint Charles, the average temperature is 24°C (75°F), with maximums reaching up to 36°C (97°F) and minimums dropping as low as 11°C (52°F). This makes it a great time for travelers to enjoy warm days while also being prepared for cooler evenings.

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

The chart illustrates August 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, August typically has an average temperature of 24°C (75°F), with highs reaching up to 36°C (97°F) and lows dropping to around 11°C (52°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.

August Precipitation in Saint Charles

In Saint Charles in August, the precipitation amount is 76 mm (3.0 in) spread over a duration of 8 days.

August Precipitation Trends in Saint Charles

The chart displays monthly precipitation patterns in Saint Charles, with values for each month alongside August’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how August’s conditions compare to those of other months. In Saint Charles, August typically receives around 76 mm (3.0 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec4139856916311769761171344336
Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.
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August Humidity in Saint Charles

In Saint Charles in August humidity is 77%. With an average temperature of 24°C (75°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities feel stifling and may require frequent breaks to stay hydrated while exploring.

August Average Humidity in Saint Charles

This chart illustrates the average monthly humidity levels in Saint Charles, with August’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In August, 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 August generated using information from the Copernicus Climate Change Service.

August UV Index in Saint Charles

In Saint Charles in August, 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 August

The chart shows the monthly maximum UV Index (UVI) for Saint Charles in August, 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 August, the maximum UV index in Saint Charles typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec35689111098643
Data source: Saint Charles August 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 August 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 August’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 August’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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