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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 reaches a pleasant 22°C (72°F). However, temperatures can vary significantly, with a minimum of 7°C (45°F) and soaring to a maximum of 35°C (95°F). Expect about 76 mm (3.0 in) of precipitation spread across 11 days, and with an average humidity of 80%, be prepared for a warm and somewhat moist atmosphere!

August Temperature in Saint Charles

In August in Saint Charles, the average temperature is 22°C (72°F). The maximum can reach 35°C (95°F), while the minimum can drop to as low as 7°C (45°F). This diverse temperature range makes it a perfect time for travelers to enjoy both warm days and cooler evenings while exploring the sights.

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 22°C (72°F), with highs reaching up to 35°C (95°F) and lows dropping to around 7°C (45°F).
JanFebMarAprMayJunJulAugSepOctNovDec252636465969747264533831
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 total precipitation amount is 76 mm (3.0 in), recorded over a period of 11 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 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec5963618811512166761011126060
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 80%. With an average temperature of 22°C (72°F), this humidity feels like a warm, enveloping blanket that can quickly sap your energy while traveling, making you feel sticky and uncomfortable if you're not prepared.

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 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%85%86%80%80%80%81%80%84%90%86%
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.
JanFebMarAprMayJunJulAugSepOctNovDec24589101097532
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-4°C (25°F)59 mm (2.3 inches)88%low
February Weather-3°C (26°F)63 mm (2.5 inches)87%moderate
March Weather2°C (36°F)61 mm (2.4 inches)85%moderate
April Weather8°C (46°F)88 mm (3.4 inches)86%very high
May Weather15°C (59°F)115 mm (4.5 inches)80%very high
June Weather21°C (70°F)121 mm (4.8 inches)80%very high
July Weather23°C (75°F)66 mm (2.6 inches)80%very high
August Weather22°C (72°F)76 mm (3.0 inches)80%very high
September Weather18°C (65°F)101 mm (4.0 inches)80%high
October Weather11°C (53°F)112 mm (4.4 inches)84%moderate
November Weather3°C (38°F)60 mm (2.4 inches)89%moderate
December Weather0°C (32°F)60 mm (2.4 inches)86%low

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