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September Weather in Grand Rapids, United States

Last updated: June 24, 2025

In Grand Rapids, United States, the average temperature in September hovers around 20°C (68°F), with lows dipping to 5°C (40°F) and highs peaking at 34°C (93°F). Expect a total precipitation of 59 mm (2.3 in) spread over 9 days, contributing to the area's notably high average humidity of 78%.

September Temperature in Grand Rapids

In September in Grand Rapids, the average temperature is 20°C (68°F), with maximums reaching up to 34°C (93°F) and minimums dropping as low as 5°C (40°F). It's a great time to visit for those who enjoy mild weather with the option of some warm days.

September Weather in Grand Rapids: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Grand Rapids, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Grand Rapids, September typically has an average temperature of 20°C (68°F), with highs reaching up to 34°C (93°F) and lows dropping to around 5°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec283039496272767368564134
Data source: Temperature data for Grand Rapids 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 Grand Rapids

In Grand Rapids in September, the precipitation amount is 59 mm (2.3 in) over the course of 9 days.

September Precipitation Trends in Grand Rapids

The chart displays monthly precipitation patterns in Grand Rapids, 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 Grand Rapids, September typically receives around 59 mm (2.3 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec697284931451061128859928356
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Grand Rapids

In Grand Rapids in September humidity is 78%. With an average temperature of 20°C (68°F), this humidity feels like a warm, enveloping blanket that makes exploring the sights a bit sticky, so travelers should stay hydrated and take frequent breaks in the shade.

September Average Humidity in Grand Rapids

This chart illustrates the average monthly humidity levels in Grand Rapids, 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 Grand Rapids is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%87%88%81%82%81%78%78%82%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Grand Rapids

In Grand Rapids 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 Grand Rapids.

Maximum UV Index Levels in Grand Rapids for September

The chart shows the monthly maximum UV Index (UVI) for Grand Rapids 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 Grand Rapids typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Grand Rapids 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 Grand Rapids Compares to Other Months

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

This table compares monthly weather conditions in Grand Rapids, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)69 mm (2.7 inches)88%moderate
February Weather-1°C (30°F)72 mm (2.8 inches)87%moderate
March Weather4°C (40°F)84 mm (3.3 inches)87%high
April Weather10°C (49°F)93 mm (3.7 inches)87%very high
May Weather16°C (62°F)145 mm (5.7 inches)81%very high
June Weather22°C (72°F)106 mm (4.2 inches)82%very high
July Weather24°C (76°F)112 mm (4.4 inches)81%very high
August Weather23°C (74°F)88 mm (3.5 inches)78%very high
September Weather20°C (68°F)59 mm (2.3 inches)78%very high
October Weather14°C (57°F)92 mm (3.6 inches)82%high
November Weather5°C (41°F)83 mm (3.3 inches)89%moderate
December Weather1°C (35°F)56 mm (2.2 inches)86%low

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