Measurements:
°C
°F
Mackinac Island
18°F
N 22 mph
Feels like: -2°F
Precip: 0%
World Resorts USA Mackinac Island Weather

Mackinac Island Sea Water Temperature

Current Sea Water Temperature:
+40.4°F
Maximum Sea Water Temperature in December: 44.8°F
Minimum Sea Water Temperature in December: 34.6°F
Average water temperature in December: 38.9°F

Sea Water Temperature for the Last 10 Days:

December 04 40.4°F November 29 42.8°F
December 03 40.4°F November 28 42.4°F
December 02 40.4°F November 27 43.0°F
December 01 41.6°F November 26 43.4°F
November 30 42.0°F November 25 43.8°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: 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 19.9 °F
January 21.2 °F
March 29.0 °F
The most rainy months:
August 3 days
May 2 days
July 2 days
The most windy months:
November 13 mph
December 12 mph
April 11 mph

Mackinac Island on the Weather Map

USA Resorts:
NAME
Chicago 0
Hawaii +78
Honolulu +78
Houston +46
Las Vegas +40
Los Angeles +52
Maui +72
Miami +72
Miami Beach +80
New York +18
San Diego +54
San Francisco +46
Sarasota +62
Tampa +62
Washington +28
24 Hours Weather Forecast
Mackinac Island
Local time: 02:18
05 dec, friday
0300 18°F
N
22 mph
0600 22°F
NE
24 mph
0900 26°F
NE
22 mph
1200 26°F
NE
19 mph
1500 28°F
NE
16 mph
1800 30°F
NE
16 mph
2100 30°F
NE
16 mph
06 dec, saturday
0000 30°F
E
17 mph