Detroit
Michigan, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and Climate
Detroit, MI

The downtown city of Detroit, Michigan viewed from a bird
The downtown city of Detroit, Michigan viewed from a bird's eye angle
September is a transitional month into autumn, and its first few days remain summer warm and pleasant. The afternoons receive showers of rain for approximately twelve days to fetch moderately high precipitation of 3.1" (78.7mm). The nights and early mornings feel mildly cool, but the days are more vibrant with eight hours of sunshine, and pleasant temperatures in the range of 57.2°F (14°C) and 73.4°F (23°C).
Expect the lakes' temperature to drop to 68°F (20°C) but still within the range of warm and tolerable.
  • The average high temperature in September: 23.3°C

The warmest month (with the highest average high temperature) is July (28.6°C).
The month with the lowest average high temperature is January (0°C).

  • The average low temperature in September: 12.6°C

The month with the highest average low temperature is July (17.7°C).
The coldest month (with the lowest average low temperature) is January (-7.2°C).

  • The average humidity in September: 73.4%

The month with the highest relative humidity is December (76.7%).
The month with the lowest relative humidity is May (65.3%).

  • The average rainfall in September: 83.1mm

The wettest month (with the highest rainfall) is June (89.4mm).
The driest month (with the lowest rainfall) is January (49.8mm).

  • The average rainfall days in September: 9.5 days

The month with the highest number of rainy days is December (13.7 days).
The month with the lowest number of rainy days is September (9.5 days).

  • The average snowfall in September: 0mm

The month with the highest snowfall is January (317.5mm).
Months with the lowest snowfall are May, June, July, August and September (0mm).

  • The average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (10.4 days).
Months with the lowest number of snowfall days are May, June, July, August and September (0 days).

  • The average sea temperature in September: 20°C

The best month for swimming (with the highest average sea temperature) is August (23°C).
Coldest months (with the lowest average sea temperature) are February and March (2°C).

  • The average daylight in September: 12h

Months with the longest days are May, June and July (Average daylight: 15h).
Months with shortest days are January and December (Average daylight: 9h).

  • The average sunshine in September: 7.6h

The month with most sunshine is July (Average sunshine: 10.2h).
The month with least sunshine is December (Average sunshine: 2.8h).

  • The average UV index in September: 6

The month with the highest UV index is July (UV index 9).
Months with the lowest UV index are January and December (UV index 1).

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