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September Weather in Mason City, United States

Last updated: June 24, 2025

In September, the average temperature in Mason City, United States hovers around 21°C (71°F), creating a pleasant atmosphere for outdoor activities. Be prepared for a potential minimum of 6°C (42°F) and a maximum soaring to 35°C (95°F). During this month, you can expect approximately 68 mm (2.7 in) of precipitation spread over 6 days, along with an average humidity of 80%. Enjoy the unique climate while making the most of your stay!

September Temperature in Mason City

In September in Mason City, the average temperature is 21°C (71°F). Maximums can reach 35°C (95°F) and minimums can be as low as 6°C (42°F). This makes it an ideal time for travelers to enjoy mild weather while exploring the area's attractions.

September Weather in Mason City: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Mason City, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mason City, September typically has an average temperature of 21°C (71°F), with highs reaching up to 35°C (95°F) and lows dropping to around 6°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec283143526575777470574135
Data source: Temperature data for Mason City 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.

September Precipitation in Mason City

In Mason City in September, the precipitation amount is 68 mm (2.7 in) spread over the course of 6 days.

September Precipitation Trends in Mason City

The chart displays monthly precipitation patterns in Mason City, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Mason City, September typically receives around 68 mm (2.7 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec666812312015613611797681146353
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Mason City

In Mason City in September humidity is 80%. With an average temperature of 21°C (71°F), this humidity feels like a warm, heavy blanket wrapping around you, making outdoor activities feel more exhausting and requiring frequent breaks to stay hydrated.

September Average Humidity in Mason City

This chart illustrates the average monthly humidity levels in Mason City, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Mason City is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%83%84%85%79%82%80%81%80%82%88%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Mason City

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.

Maximum UV Index Levels in Mason City for September

The chart shows the monthly maximum UV Index (UVI) for Mason City in September, 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 September, the maximum UV index in Mason City typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357810111098642
Data source: Mason City September 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 September Weather in Mason City Compares to Other Months

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.

This table compares monthly weather conditions in Mason City, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (28°F)66 mm (2.6 inches)82%moderate
February Weather-1°C (31°F)67 mm (2.7 inches)83%moderate
March Weather6°C (43°F)123 mm (4.8 inches)84%high
April Weather11°C (52°F)120 mm (4.7 inches)85%very high
May Weather18°C (65°F)156 mm (6.1 inches)79%very high
June Weather24°C (75°F)136 mm (5.4 inches)82%extreme
July Weather25°C (78°F)117 mm (4.6 inches)80%very high
August Weather24°C (75°F)97 mm (3.8 inches)81%very high
September Weather21°C (71°F)68 mm (2.7 inches)80%very high
October Weather14°C (57°F)114 mm (4.5 inches)82%high
November Weather5°C (42°F)63 mm (2.5 inches)88%moderate
December Weather2°C (36°F)53 mm (2.1 inches)84%low

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