Wet suit or not for open water swimming?

If its under 55 I wear a wet suit, altho I did swim in San Francisco on 2 occasions for just under an hour, both times in 52 degree water with no wet suit,,,BUT I did wear a blueseventy neoprene cap with a chin strap and silicone earplugs. 3 weeks ago I swam in the Pacific at Coronado Island in water that I guessed was low 50`s,..no wetsuit, AND no neoprene cap and no earplugs. MY HEAD FROOZE,..I lasted 15 minutes. I love 65 degree water,..no over heating. Sunday I swam in Lake Michigan with water temp in the mid 50`s. I wore a wetsuit because I was swimming alone, AND it was fresh water and I wanted the extra buoyancy. When I got out a couple hundred yards, I could feel the temp. drop quite a bit.

If its under 55 I wear a wet suit, altho I did swim in San Francisco on 2 occasions for just under an hour, both times in 52 degree water with no wet suit,,,BUT I did wear a blueseventy neoprene cap with a chin strap and silicone earplugs. 3 weeks ago I swam in the Pacific at Coronado Island in water that I guessed was low 50`s,..no wetsuit, AND no neoprene cap and no earplugs. MY HEAD FROOZE,..I lasted 15 minutes. I love 65 degree water,..no over heating. Sunday I swam in Lake Michigan with water temp in the mid 50`s. I wore a wetsuit because I was swimming alone, AND it was fresh water and I wanted the extra buoyancy. When I got out a couple hundred yards, I could feel the temp. drop quite a bit.