September weather forecastMackinac Island, MI
September
Weather in September
September ushers in autumn on Mackinac Island. There is a slight dip in temperatures, setting the stage for the fall. The days start to become shorter and the leaves begin to change their colour. Sunshine hours decrease gradually and the weather becomes more variable. Despite these changes, September often remains a pleasant and comfortable month.Temperature
The advent of September brings a slight shift in average high-temperature, moving from a pleasant 71.1°F (21.7°C) in August to an enjoyable 64.8°F (18.2°C). Mackinac Island encounters an average low-temperature of 53.1°F (11.7°C) during September nights.Humidity
The average relative humidity in September is 79%.Rainfall
In September, the rain falls for 11.4 days. Throughout September, 1.73" (44mm) of precipitation is accumulated. Throughout the year, there are 131 rainfall days, and 21.22" (539mm) of precipitation is accumulated.Snowfall
In Mackinac Island, snow does not fall in June through September.Ocean temperature
In Mackinac Island, Michigan, the average seawater temperature in September is 59°F (15°C).Note: Swimming in water with a temperature of 59°F (15°C) is not a pleasurable experience for the majority. As the temperature falls below 69.8°F (21°C), it becomes increasingly hard to control one's breathing.
Daylight
In September, the average length of the day is 12h and 31min.On the first day of September, sunrise is at 7:00 am and sunset at 8:16 pm. On the last day of the month, sunrise is at 7:36 am and sunset at 7:19 pm EDT.
Sunshine
In Mackinac Island, Michigan, the average sunshine in September is 7.8h.UV index
In September, the average daily maximum UV index in Mackinac Island is 3. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.Note: In September, the average maximum UV index of 3 translates into the following recommendations:
Be mindful. Individuals with a lighter skin tone may suffer burns in less than 30 minutes. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Mackinac Island, MI
- Average high temperature in September: 64.8°F
The warmest month (with the highest average high temperature) is July (71.4°F).
The month with the lowest average high temperature is January (23.4°F).
- Average low temperature in September: 53.1°F
The month with the highest average low temperature is August (58.6°F).
The coldest month (with the lowest average low temperature) is February (14.4°F).
Average pressure in September
Mackinac Island, MI
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is March (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Mackinac Island, MI
- Average wind speed in September: 8.5mph
The windiest months (with the highest average wind speed) are November and December (10.9mph).
The calmest months (with the lowest average wind speed) are June and July (7.6mph).
Average humidity in September
Mackinac Island, MI
- Average humidity in September: 79%
The months with the highest relative humidity are January and February (89%).
The month with the lowest relative humidity is May (75%).
Average rainfall in September
Mackinac Island, MI
- Average rainfall in September: 1.73"
The wettest month (with the highest rainfall) is October (2.72").
The driest month (with the least rainfall) is January (1.3").
Average rainfall days in September
Mackinac Island, MI
- Average rainfall days in September: 11.4 days
The month with the highest number of rainy days is October (16.5 days).
The month with the least rainy days is February (5.3 days).
Average snowfall in September
Mackinac Island, MI
- Average snowfall in September: 0"
The month with the highest snowfall is January (5.91").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Mackinac Island, MI
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (21.9 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average sea temperature in September
Mackinac Island, MI
- Average sea temperature in September: 59°F
The best month for swimming (with the highest average sea temperature) is August (61°F).
The coldest months (with the lowest average sea temperature) are February, March and April (36°F).
Average daylight in September /
Average sunshine in September
Mackinac Island, MI
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in September: 7h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 1h and 54min).
Average sunshine days in September
Mackinac Island, MI
- Average sunshine days in September: 16.9 days
The month with the most sunshine days is September (16.9 days).
The month with the least sunshine days is January (7.1 days).
Average UV index in September
Mackinac Island, MI
- Average UV index in September: 3
The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, March, November and December (UV index 1).
Average cloud cover in September
Mackinac Island, MI
- Average cloud cover in September: 34
The month with the most cloud cover is January (Cloud cover 80).
The months with the least cloud cover are July and August (Cloud cover 32).
Average visibility in September
Mackinac Island, MI
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March and December (5mi).
