September weather forecast
Ann Arbor, MI

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The vast University of Michigan Law School Campus in Ann Arbor, Michigan
The vast University of Michigan Law School Campus in Ann Arbor, Michigan

Weather in September

September in Ann Arbor marks the beginning of fall and triggers a gradual decline in temperature. It is a transitional period, as hot summer afternoons make way for crisp autumn evenings. While the leaves begin to burst into autumn colors, residents prepare for cooler weather. As autumn sets in, rainfall tends to decrease, giving way to drier days. A noteworthy factor in September is the decrease in high temperature from 78.3°F (25.7°C) in August to 72.5°F (22.5°C), indicating the commencement of cool weather.

Temperature

September signifies a gentle decline in Ann Arbor's average high-temperature, easing from a warm 78.3°F (25.7°C) in August to an agreeable 72.5°F (22.5°C). Ann Arbor's nights in September experience an average temperature drop to a cool 54.9°F (12.7°C).

Humidity

The average relative humidity in September in Ann Arbor is 79%.

Rainfall

In Ann Arbor, in September, during 13.4 rainfall days, 1.46" (37mm) of precipitation is typically accumulated. In Ann Arbor, during the entire year, the rain falls for 144.9 days and collects up to 18.82" (478mm) of precipitation.

Snowfall

June through September are months without snowfall.

Daylight

The average length of the day in September in Ann Arbor, Michigan, is 12h and 28min.
On the first day of the month, sunrise is at 7:01 am and sunset at 8:08 pm. On the last day of September, sunrise is at 7:31 am and sunset at 7:17 pm EDT.

Sunshine

In Ann Arbor, the average sunshine in September is 8.1h.

UV index

In September, the average daily maximum UV index in Ann Arbor is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for the average person.
Note: In September, the maximum UV index of 4 suggests these recommendations:
Undertake protective steps - Recommendations to avoid sunburn are issued. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses.
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Frequently asked questions

What is the temperature in September in Ann Arbor?

Ann Arbor in September has an average high-temperature of 72.5°F (22.5°C) and an average low-temperature of 54.9°F (12.7°C).

What is the average humidity in September in Ann Arbor?

In September, the average relative humidity in Ann Arbor is 79%.

How much does it rain in Ann Arbor in September?

In September, in Ann Arbor, the rain falls for 13.4 days. Throughout September, 1.46" (37mm) of precipitation is accumulated.

When it does not snow in Ann Arbor?

June through September are months without snowfall in Ann Arbor, Michigan.

Does it snow in Ann Arbor in September?

In Ann Arbor, in September, it doesn't snow. In October, it regularly snows.

What is the average length of the day in September in Ann Arbor?

In September, the average day length in Ann Arbor, Michigan, is 12h and 28min.

What time are sunrise and sunset in September in Ann Arbor?

In September, on the first day of the month, sunrise is at 7:01 am and sunset at 8:08 pm. On the last day of the month, in Ann Arbor, Michigan, sunrise is at 7:31 am and sunset at 7:17 pm EDT.

How many hours of sunshine does Ann Arbor have in September?

In Ann Arbor, Michigan, the average sunshine duration in September is 8.1h.

How high is the UV index in September in Ann Arbor?

The average daily maximum UV index in September in Ann Arbor is 4. A UV Index value of 3 to 5 symbolizes a medium hazard to health from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Ann Arbor, MI

Average temperature in September - Ann Arbor, MI
  • Average high temperature in September: 72.5°F

The warmest month (with the highest average high temperature) is July (79.9°F).
The month with the lowest average high temperature is January (28.2°F).

  • Average low temperature in September: 54.9°F

The month with the highest average low temperature is July (62.2°F).
The coldest month (with the lowest average low temperature) is January (17.8°F).

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Average pressure in September
Ann Arbor, MI

Average pressure in September - Ann Arbor, MI
  • Average pressure in September: 30.04"Hg

The months with the highest atmospheric pressure are March and November (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

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Average wind speed in September
Ann Arbor, MI

Average wind speed in September - Ann Arbor, MI
  • Average wind speed in September: 7.1mph

The windiest month (with the highest average wind speed) is January (10.1mph).
The calmest month (with the lowest average wind speed) is July (6.4mph).

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Average humidity in September
Ann Arbor, MI

Average humidity in September - Ann Arbor, MI
  • Average humidity in September: 79%

The months with the highest relative humidity are January and February (86%).
The month with the lowest relative humidity is April (76%).

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Average rainfall in September
Ann Arbor, MI

Average rainfall in September - Ann Arbor, MI
  • Average rainfall in September: 1.46"

The wettest month (with the highest rainfall) is May (2.4").
The driest month (with the least rainfall) is December (0.87").

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Average rainfall days in September
Ann Arbor, MI

Average rainfall days in September - Ann Arbor, MI
  • Average rainfall days in September: 13.4 days

The month with the highest number of rainy days is May (18.2 days).
The month with the least rainy days is January (5.2 days).

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Average snowfall in September
Ann Arbor, MI

Average snowfall in September - Ann Arbor, MI
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.72").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in September
Ann Arbor, MI

Average snowfall days in September - Ann Arbor, MI
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (11.5 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight in September /
Average sunshine in September
Ann Arbor, MI

Average daylight in September / Average sunshine in September - Ann Arbor, MI
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in September: 8h and 1min

The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).

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Average sunshine days in September
Ann Arbor, MI

Average sunshine days in September - Ann Arbor, MI
  • Average sunshine days in September: 14.6 days

The month with the most sunshine days is October (17.5 days).
The month with the least sunshine days is July (10.3 days).

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Average UV index in September
Ann Arbor, MI

Average UV index in September - Ann Arbor, MI
  • Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).

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Average cloud cover in September
Ann Arbor, MI

Average cloud cover in September - Ann Arbor, MI
  • Average cloud cover in September: 34

The month with the most cloud cover is January (Cloud cover 68).
The month with the least cloud cover is July (Cloud cover 29).

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Average visibility in September
Ann Arbor, MI

Average visibility in September - Ann Arbor, MI
  • Average visibility in September: 6mi

The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).

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Ann Arbor, Michigan, USA

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