I have just, in the past few minutes, pulled out of a planned skinny dip with a pal of mine. She's a hardy perennial and has been swimming throughout the winter, including when the water temperature was 2°C and the air temperature -2°C. She was perfectly understanding.
High tide is at 10.23 this evening, which would have been perfect had we been enjoying last Monday's weather instead of this. We haven't got the heating on, but are are dressed in more clothes than usual. 13°C outside at the moment, 19°C inside.