Measurements:
°C
°F
Mackinac Island
72°F
SE 5 mph
Feels like: 72°F
Precip: 14%
World Resorts USA Mackinac Island Weather

Mackinac Island Sea Water Temperature

Current Sea Water Temperature:
+68.0°F
Maximum Sea Water Temperature in August: 75.8°F
Minimum Sea Water Temperature in August: 61.0°F
Average water temperature in August: 69.4°F

Sea Water Temperature for the Last 10 Days:

August 25 68.0°F August 20 70.8°F
August 24 70.6°F August 19 71.4°F
August 23 70.8°F August 18 71.8°F
August 22 70.8°F August 17 72.8°F
August 21 71.0°F August 16 72.8°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: 2026 2025 2024

The average sea surface temperature in August 2026 for Mackinac Island was 71.4°F. The maximum and minimum values were 68.0°F and 73.8°F respectively.

Sea Water Temperature in July

Select Year: 2026 2025 2024

The average sea surface temperature in July 2026 for Mackinac Island was 68.7°F. The maximum and minimum values were 63.6°F and 73.2°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 16 days
August 14 days
June 12 days
The most warm months:
August 71.6 °F
July 71.6 °F
September 64.4 °F
Warmest sea temperature:
August 69.6 °F
July 67.0 °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
April 2 days
July 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 +80
Chicago +80
Hawaii +84
Houston +106
Las Vegas +116
Los Angeles +96
Maui +70
Miami +92
Myrtle Beach +84
New York +82
San Diego +96
San Francisco +64
Santa Monica +86
Sarasota +92
Washington +84
24 Hours Weather Forecast
Mackinac Island
Local time: 17:37
25 aug, tuesday
1800 72°F
SE
5 mph
2100 66°F
NW
12 mph
26 aug, wednesday
0000 62°F
N
11 mph
0300 68°F
N
11 mph
0600 66°F
N
15 mph
0900 66°F
N
17 mph
1200 70°F
NE
16 mph
1500 74°F
E
16 mph