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September Weather in Grass Lake, United States

Last updated: June 24, 2025

In September, the average temperature in Grass Lake, United States is a comfortable 19°C (66°F). Expect temperatures to range from a chilly 2°C (36°F) at night up to a warm 33°C (92°F) during the day. With 74 mm (2.9 in) of precipitation spread over 8 days, it's wise to prepare for some rain. The average humidity sits at a brisk 80%, making the air feel a little more refreshing.

September Temperature in Grass Lake

In September in Grass Lake, the average temperature is 19°C (66°F). The maximum can reach 33°C (92°F) and the minimum can be as low as 2°C (36°F). This diverse climate makes Grass Lake an ideal destination for travelers looking to experience a range of temperatures and activities.

September Weather in Grass Lake: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Grass Lake, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Grass Lake, September typically has an average temperature of 19°C (66°F), with highs reaching up to 33°C (92°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec262737476070747265543932
Data source: Temperature data for Grass Lake 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 Grass Lake

In Grass Lake in September, the precipitation amount is 74 mm (2.9 in) over a period of 8 days.

September Precipitation Trends in Grass Lake

The chart displays monthly precipitation patterns in Grass Lake, 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 Grass Lake, September typically receives around 74 mm (2.9 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec656978921238410165741097554
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Grass Lake

In Grass Lake in September humidity is 80%. With an average temperature of 19°C (66°F), this humidity feels like a warm, thick blanket wrapping around you, making outdoor activities feel more strenuous and sticky, which can ultimately dampen the experience of traveling.

September Average Humidity in Grass Lake

This chart illustrates the average monthly humidity levels in Grass Lake, 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 Grass Lake is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%85%86%80%80%80%81%80%84%90%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Grass Lake

In Grass Lake in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Grass Lake.

Maximum UV Index Levels in Grass Lake for September

The chart shows the monthly maximum UV Index (UVI) for Grass Lake 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 Grass Lake typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24599101097542
Data source: Grass Lake 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 Grass Lake Compares to Other Months

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

This table compares monthly weather conditions in Grass Lake, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (26°F)65 mm (2.6 inches)88%low
February Weather-3°C (28°F)69 mm (2.7 inches)87%moderate
March Weather3°C (38°F)78 mm (3.1 inches)85%moderate
April Weather8°C (47°F)92 mm (3.6 inches)86%very high
May Weather15°C (60°F)123 mm (4.8 inches)80%very high
June Weather21°C (70°F)84 mm (3.3 inches)80%very high
July Weather24°C (75°F)101 mm (4.0 inches)80%very high
August Weather22°C (72°F)65 mm (2.6 inches)80%very high
September Weather19°C (66°F)74 mm (2.9 inches)80%high
October Weather12°C (54°F)109 mm (4.3 inches)84%moderate
November Weather4°C (39°F)75 mm (3.0 inches)89%moderate
December Weather0°C (33°F)54 mm (2.1 inches)86%low

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