Measurements:
°C
°F
Mackinac Island
54°F
SE 5 mph
Feels like: 52°F
Precip: 0%
World Resorts USA Mackinac Island Weather

Mackinac Island Sea Water Temperature

Current Sea Water Temperature:
+40.0°F
Maximum Sea Water Temperature in May: 52.8°F
Minimum Sea Water Temperature in May: 34.6°F
Average water temperature in May: 41.7°F

Sea Water Temperature for the Last 10 Days:

May 14 40.0°F May 09 37.4°F
May 13 39.6°F May 08 37.4°F
May 12 39.0°F May 07 36.8°F
May 11 38.6°F May 06 37.4°F
May 10 39.0°F May 05 36.6°F

When is the Warmest Sea for Mackinac Island?

According to our data for the last three years for Mackinac Island the highest average sea water temperature was in August, July and September.

Average Water Temperature by Month, °F

Sea Water Temperature in August

Select Year: 2025 2024 2023

The average sea surface temperature in August 2025 for Mackinac Island was 71.6°F. The maximum and minimum values were 67.0°F and 74.8°F respectively.

Sea Water Temperature in July

Select Year: 2025 2024 2023

The average sea surface temperature in July 2025 for Mackinac Island was 67.6°F. The maximum and minimum values were 60.0°F and 73.0°F respectively.

Sea Water Temperature in September

Select Year: 2025 2024 2023

The average sea surface temperature in September 2025 for Mackinac Island was 63.3°F. The maximum and minimum values were 60.4°F and 69.0°F respectively.

Best Time to Visit Mackinac Island
The most sunny months:
July 14 days
August 14 days
September 12 days
The most warm months:
August 71.6 °F
July 71.5 °F
September 64.4 °F
Warmest sea temperature:
August 69.2 °F
July 66.8 °F
September 64.1 °F
The most cold months:
February 20.1 °F
January 20.4 °F
December 28.6 °F
The most rainy months:
August 3 days
May 2 days
April 2 days
The most windy months:
November 13 mph
December 13 mph
April 11 mph

Mackinac Island on the Weather Map

USA Resorts:
NAME
Boston +56
Chicago +56
Hawaii +78
Honolulu +78
Houston +98
Las Vegas +102
Los Angeles +76
Maui +72
Miami +90
Miami Beach +92
New York +70
San Diego +72
San Francisco +72
Sarasota +96
Tampa +96
24 Hours Weather Forecast
Mackinac Island
Local time: 14:01
14 may, thursday
1500 54°F
SE
5 mph
1800 54°F
E
9 mph
2100 46°F
E
8 mph
15 may, friday
0000 44°F
NE
5 mph
0300 44°F
N
6 mph
0600 44°F
N
8 mph
0900 48°F
N
9 mph
1200 52°F
N
11 mph