CHICAGO (STMW) – Water temperatures in the southern part of Lake Michigan reached a “remarkable” 80 degrees Friday — sooner than any other year thanks to a warm winter combined with July’s searing heat wave, forecasters say.

The buoy that measures water temperatures in the southern portion of the lake recorded two hourly readings of 80 degrees, something that’s happened only six other times since 1981, according to the National Weather Service.

The reading also breaks the record for earliest day in the year when the lake reached the 80-degree mark, forecasters say. Last summer and the summer of 2010 didn’t see lake waters reach 80 degrees until July 21, which stood as the previous record.

Nine months of above-normal temperatures are partially responsible, as is early July’s heat wave, according to the weather service. Water temperatures have spiked 10 degrees since just July 1.

Those warm temperatures are “remarkable” not just for how soon they’ve arrived, but also for how far above average water temperatures they are for this time of year.

Friday’s average water temperature for the entire day was measured at 78 degrees, a full 15 degrees above average water temperatures for the date, according to the weather service.

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