Last updated: June 24, 2025
In May, the average temperature in Saint Charles, United States hovers around 15°C (59°F). Visitors should be prepared for a wide range of temperatures, as it can dip to a chilly -1°C (30°F) and soar to a warm 35°C (95°F). With 152 mm (6.0 in) of rainfall spread over approximately 15 days, a light raincoat can come in handy. The air carries a notable average humidity of 75%, adding to the region's unique climate experience.
In May in Saint Charles, the average temperature is 15°C (59°F). Maximum temperatures can reach 35°C (95°F), while minimums can drop as low as -1°C (30°F). It's advisable to pack for a wide range of weather conditions to fully enjoy your travels in this diverse climate.
In Saint Charles in May, the precipitation amount is 152 mm (6.0 in) over the course of 15 days.
In Saint Charles in May, humidity is 75%. With an average temperature of 15°C (59°F), this humidity feels like a warm blanket enveloping you, making it feel more oppressive than refreshing, which can be a challenge for travelers seeking comfort while exploring the area.
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.
UV Risk Categories
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.
| 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 |