Last updated: June 24, 2025
In August, the average temperature in Saint Charles, United States hovers around 21°C (70°F), creating a pleasant atmosphere for outdoor activities. Temperature extremes can vary, with a minimum of 10°C (50°F) and a maximum reaching up to 34°C (94°F). You'll want to prepare for some rainfall, as 126 mm (5.0 in) of precipitation may be expected over 11 days. Relative humidity sits at a comfortable 69%, making it an ideal time to explore the area's beauty.
In August in Saint Charles, the average temperature is 21°C (70°F). Maximums can reach 34°C (94°F) and minimums can be as low as 10°C (50°F). This makes it an ideal time for travelers to enjoy pleasant weather while exploring the area's attractions.
In Saint Charles in August, the total precipitation amount is 126 mm (5.0 in) spread over 11 days.
In Saint Charles in August humidity is 69%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making outdoor activities enjoyable but requiring occasional breaks for hydration and shade during your travels.
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.
UV Risk Categories
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.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (18°F) | 36 mm (1.4 inches) | 84% | moderate |
| February Weather | -7°C (19°F) | 48 mm (1.9 inches) | 85% | moderate |
| March Weather | 1°C (34°F) | 57 mm (2.2 inches) | 84% | moderate |
| April Weather | 7°C (44°F) | 86 mm (3.4 inches) | 83% | very high |
| May Weather | 15°C (59°F) | 152 mm (6.0 inches) | 75% | very high |
| June Weather | 21°C (71°F) | 151 mm (5.9 inches) | 79% | very high |
| July Weather | 23°C (74°F) | 103 mm (4.1 inches) | 75% | very high |
| August Weather | 21°C (70°F) | 126 mm (5.0 inches) | 69% | very high |
| September Weather | 18°C (64°F) | 117 mm (4.6 inches) | 74% | very high |
| October Weather | 9°C (49°F) | 118 mm (4.7 inches) | 79% | moderate |
| November Weather | 1°C (34°F) | 52 mm (2.0 inches) | 88% | moderate |
| December Weather | -4°C (26°F) | 43 mm (1.7 inches) | 82% | low |