Last updated: June 24, 2025
In September, the average temperature in Mason City, United States is a pleasant 18°C (65°F). Temperatures can range from a cool 2°C (36°F) to a warm 33°C (92°F), offering a diverse climate experience. Expect approximately 108 mm (4.2 in) of precipitation spread over 11 days, contributing to a 75% average humidity that adds a touch of moisture to the air.
In September, in Mason City, the average temperature is 18°C (65°F). The maximum can reach 33°C (92°F), while the minimum can be as low as 2°C (36°F). This temperature range makes Mason City an ideal destination for travelers seeking both warm days and cool nights.
In Mason City in September, the precipitation amount is 108 mm (4.2 in), distributed over 11 days.
In Mason City in September, humidity is 75%. With an average temperature of 18°C (65°F), this humidity feels like a warm, enveloping blanket that can make outdoor exploration feel a bit stifling, potentially leading to discomfort during travel activities.
In Mason City in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Mason City.
UV Risk Categories
Weather in Mason City varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Mason City, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (19°F) | 36 mm (1.4 inches) | 82% | moderate |
| February Weather | -8°C (18°F) | 47 mm (1.9 inches) | 84% | moderate |
| March Weather | 1°C (35°F) | 71 mm (2.8 inches) | 80% | moderate |
| April Weather | 7°C (45°F) | 80 mm (3.1 inches) | 81% | very high |
| May Weather | 15°C (60°F) | 159 mm (6.3 inches) | 74% | very high |
| June Weather | 22°C (72°F) | 132 mm (5.2 inches) | 80% | extreme |
| July Weather | 23°C (74°F) | 98 mm (3.8 inches) | 80% | very high |
| August Weather | 21°C (71°F) | 118 mm (4.7 inches) | 77% | very high |
| September Weather | 18°C (65°F) | 108 mm (4.2 inches) | 75% | very high |
| October Weather | 10°C (49°F) | 112 mm (4.4 inches) | 80% | moderate |
| November Weather | 1°C (35°F) | 49 mm (1.9 inches) | 87% | moderate |
| December Weather | -3°C (27°F) | 35 mm (1.4 inches) | 83% | moderate |