After a long cold winter and a relatively cool spring across the Great Lakes, the Lake Michigan water temperature remains very cold. The southern Lake Michigan buoy located about 50 miles southeast of Milwaukee at mid-lake has been reporting a lake surface water temperature in the middle 30s since it was deployed last Monday. Similar water temperatures have been reported by the northern Lake Michigan buoy located midway between Washington Island and North Manitou Islands.
Typically at this time of year, the average Lake Michigan water temperature is between 39 and 45 degrees. The below graph shows the Lake Michigan average surface water temperature for this year, compared to the long term average for the previous 20 years. For 2014, the lake surface temperature has been running 1 to 3 degrees below the long term average.
The next chart shows how 2014 compares to the previous 5 years.
Although surface water temperatures are not quite this cold closer to shore in the shallower waters, the water at the shore remains dangerously cold. Water temperatures are estimated to be in the upper 30s and 40s at the beaches and shoreline from Sheboygan to Kenosha. In these cold waters, hypothermia can set in as quickly as 15 minutes.
Hence despite the sunshine and mild daytime temperatures expected over the long Memorial Day weekend, swimming for any length of time in Lake Michigan is discouraged. Several people have already drowned in southern and eastern Lake Michigan this spring, most likely related to hypothermia.
Enjoy the great weather this weekend, but avoid the cold lake waters.
National Weather Service - Milwaukee/Sullivan