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September Weather in Grassau, Germany

Last updated: August 23, 2025

In September, the average temperature in Grassau, Germany hovers around 13°C (56°F), offering a mild climate for visitors. Expect temperatures to range from a chilly -1°C (31°F) at night to a warm 27°C (80°F) during the day. With an average precipitation of 146 mm (5.7 in) spread over 16 days, it's wise to pack an umbrella. Additionally, the average humidity is a comfortable 83%, making for a pleasant, albeit slightly moist, atmosphere.

September Temperature in Grassau

In September in Grassau, the average temperature is 13°C (56°F). The maximum can reach 27°C (80°F), and the minimum can be as low as -1°C (31°F). This moderate climate makes Grassau an ideal destination for travelers seeking a mix of comfortable outdoor experiences and the possibility of chilly evenings.

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

The chart illustrates September temperature patterns in Grassau, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Grassau, September typically has an average temperature of 13°C (56°F), with highs reaching up to 27°C (80°F) and lows dropping to around -1°C (31°F).
JanFebMarAprMayJunJulAugSepOctNovDec293338465363636456493932
Data source: Temperature data for Grassau 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 Grassau

In Grassau in September, the precipitation amount is 146 mm (5.7 in) spread over 16 days.

September Precipitation Trends in Grassau

The chart displays monthly precipitation patterns in Grassau, 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 Grassau, September typically receives around 146 mm (5.7 inches) of precipitation spread over approximately 16 days.
JanFebMarAprMayJunJulAugSepOctNovDec1201001119420517820619614613380145
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Grassau

In Grassau in September humidity is 83%. With an average temperature of 13°C (56°F), this humidity feels like a damp blanket wrapping around you, making travel a bit uncomfortable as the air feels heavy and the moisture clings to your skin.

September Average Humidity in Grassau

This chart illustrates the average monthly humidity levels in Grassau, 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 Grassau is approximately 83%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%89%86%83%78%79%82%80%83%90%89%90%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Grassau

In Grassau in September, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in Grassau, you can refer to this Hourly UV Index in Grassau.

Maximum UV Index Levels in Grassau for September

The chart shows the monthly maximum UV Index (UVI) for Grassau 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 Grassau typically reaches 6, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec236789986432
Data source: Grassau 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 Grassau Compares to Other Months

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

This table compares monthly weather conditions in Grassau, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)120 mm (4.7 inches)93%low
February Weather1°C (34°F)100 mm (3.9 inches)89%moderate
March Weather3°C (38°F)111 mm (4.4 inches)86%high
April Weather8°C (47°F)94 mm (3.7 inches)83%high
May Weather12°C (53°F)205 mm (8.1 inches)78%very high
June Weather17°C (63°F)178 mm (7.0 inches)79%very high
July Weather17°C (64°F)205 mm (8.1 inches)82%very high
August Weather18°C (64°F)196 mm (7.7 inches)80%very high
September Weather13°C (56°F)146 mm (5.7 inches)83%high
October Weather9°C (49°F)133 mm (5.2 inches)90%moderate
November Weather4°C (39°F)80 mm (3.1 inches)89%moderate
December Weather0°C (32°F)145 mm (5.7 inches)90%low

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