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September Weather in Grundy, United States

Last updated: June 24, 2025

In September, the average temperature in Grundy, United States is a pleasant 20°C (68°F). However, be prepared for a temperature range that can dip to a minimum of 6°C (43°F) and soar to a maximum of 33°C (91°F). Expect around 105 mm (4.1 in) of precipitation spread over 10 days, contributing to an average humidity level of 68%.

September Temperature in Grundy

In September in Grundy, the average temperature is 20°C (68°F). Maximum temperatures can reach 33°C (91°F) while minimums can drop as low as 6°C (43°F). This makes Grundy a great destination for travelers looking to enjoy mild weather with the possibility of warm days and cool nights.

September Weather in Grundy: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Grundy, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Grundy, September typically has an average temperature of 20°C (68°F), with highs reaching up to 33°C (91°F) and lows dropping to around 6°C (43°F).
JanFebMarAprMayJunJulAugSepOctNovDec364247556470747268594541
Data source: Temperature data for Grundy 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 Grundy

In Grundy in September, the precipitation amount is 105 mm (4.1 in) over the course of 10 days.

September Precipitation Trends in Grundy

The chart displays monthly precipitation patterns in Grundy, 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 Grundy, September typically receives around 105 mm (4.1 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec9816812614313815210712410513083129
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Grundy

In Grundy in September humidity is 68%. With an average temperature of 20°C (68°F), this humidity feels like a warm embrace, making it ideal for leisurely strolls while also prompting travelers to stay hydrated and seek out refreshing breaks from the heat.

September Average Humidity in Grundy

This chart illustrates the average monthly humidity levels in Grundy, 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 Grundy is approximately 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%87%86%84%83%83%79%66%68%78%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Grundy

In Grundy in September, 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 Grundy.

Maximum UV Index Levels in Grundy for September

The chart shows the monthly maximum UV Index (UVI) for Grundy 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 Grundy typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36810111111109753
Data source: Grundy 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 Grundy Compares to Other Months

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

This table compares monthly weather conditions in Grundy, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather2°C (37°F)98 mm (3.8 inches)87%moderate
February Weather5°C (42°F)168 mm (6.6 inches)87%high
March Weather8°C (47°F)126 mm (5.0 inches)86%very high
April Weather13°C (55°F)143 mm (5.6 inches)84%very high
May Weather18°C (64°F)138 mm (5.4 inches)83%extreme
June Weather21°C (70°F)152 mm (6.0 inches)83%extreme
July Weather23°C (74°F)107 mm (4.2 inches)79%extreme
August Weather22°C (72°F)124 mm (4.9 inches)66%very high
September Weather20°C (68°F)105 mm (4.1 inches)68%very high
October Weather15°C (59°F)130 mm (5.1 inches)78%high
November Weather7°C (45°F)82 mm (3.2 inches)89%moderate
December Weather5°C (41°F)129 mm (5.1 inches)86%moderate

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