Registered Coldology Practitioner, Bernard Lynch, posed the following question to Met Eireann:
“Why do the sea temp watches of a group of sea swimmers around the Cork coast always show approx a -1 degree difference to the M3 and M5 bouy registered temps on this site. Is the water close to shore colder and why?”
Columba Creamer of Met Eireann very helpfully replied:
You are correct in that sea water close to shore is at a different temperature to that in the open sea. During the winter this difference can be quite substantial and usually the open sea temperature will be warmer than that close to shore. During the summer the opposite happens and water close to shore will be warmer. Water close to shore will be cooled or warmed depending on the time of year by the nearby land mass. The tides also affect the temperature of the water especially inshore and in confined sea areas.
I attach latest sea temperature picture for Ireland’s coastal areas: