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August Weather in O'Fallon, United States

Last updated: June 24, 2025

In O'Fallon, United States, the average temperature in August hovers around 24°C (76°F). You can expect a minimum of 13°C (56°F) and a maximum of 35°C (96°F), making it a month of varied warmth. Rainfall totals around 139 mm (5.5 in) across 12 days, contributing to an average humidity of 80%. Prepare for a blend of sun and occasional showers!

August Temperature in O'Fallon

In August in O'Fallon, the average temperature is 24°C (76°F). Maximums can reach 35°C (96°F), and minimums can drop as low as 13°C (56°F). This makes it an ideal time for travelers to enjoy a variety of outdoor activities and pleasant weather in O'Fallon.

August Weather in O'Fallon: Daily Temperature Highs, Lows, and Averages

The chart illustrates August temperature patterns in O'Fallon, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In O'Fallon, August typically has an average temperature of 24°C (76°F), with highs reaching up to 35°C (96°F) and lows dropping to around 13°C (56°F).
JanFebMarAprMayJunJulAugSepOctNovDec323546556776797672594439
Data source: Temperature data for O'Fallon 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 O'Fallon

In O'Fallon, in August, the precipitation amount is 139 mm (5.5 in) over a span of 12 days.

August Precipitation Trends in O'Fallon

The chart displays monthly precipitation patterns in O'Fallon, 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 O'Fallon, August typically receives around 139 mm (5.5 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec72781281211458497139561106852
Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.
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August Humidity in O'Fallon

In O'Fallon in August humidity is 80%. With an average temperature of 24°C (76°F), this humidity feels like a warm, sticky embrace that can make exploring outdoors quite draining, so it's essential to stay hydrated and take breaks in the shade while traveling.

August Average Humidity in O'Fallon

This chart illustrates the average monthly humidity levels in O'Fallon, 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 O'Fallon is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%80%82%83%81%80%76%76%85%86%
Data source: Humidity data for August generated using information from the Copernicus Climate Change Service.

August UV Index in O'Fallon

In O'Fallon in August, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in O'Fallon.

Maximum UV Index Levels in O'Fallon for August

The chart shows the monthly maximum UV Index (UVI) for O'Fallon 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 O'Fallon typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109653
Data source: O'Fallon 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 O'Fallon Compares to Other Months

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

This table compares monthly weather conditions in O'Fallon, showing how August’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (32°F)72 mm (2.9 inches)82%moderate
February Weather2°C (35°F)78 mm (3.1 inches)80%moderate
March Weather8°C (47°F)128 mm (5.0 inches)80%high
April Weather13°C (55°F)121 mm (4.8 inches)80%very high
May Weather19°C (67°F)145 mm (5.7 inches)82%very high
June Weather25°C (76°F)84 mm (3.3 inches)83%extreme
July Weather26°C (80°F)97 mm (3.8 inches)81%extreme
August Weather24°C (76°F)139 mm (5.5 inches)80%very high
September Weather22°C (72°F)56 mm (2.2 inches)76%very high
October Weather15°C (59°F)110 mm (4.3 inches)76%high
November Weather7°C (44°F)68 mm (2.7 inches)85%moderate
December Weather4°C (39°F)52 mm (2.1 inches)86%moderate

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