When's the water at Kiel warm enough for swimming?

I’m planning a trip to Kiel in May and was wondering if the water in the Baltic there will be warm enough for swimming. A few years ago I was there in August and the water was lovely, but maybe May is too early in the year for the beach. Is there some website which gives typical water temperatures throughout the year? I found lots of weather sites giving the current water temperature, but obviously that doesn’t help me.

I sincerely doubt that it’s warm enough in May, but, then again, in my opinion no part of the Baltic is ever warm enough to swim in.

I think the temperature varies a great deal with the location. The water in Kiel, as I said, was quite warm, and was full of swimmers. A few days later we went to the beach at Svetlogorsk, near Kaliningrad (Königsberg), and it was positively frigid.

Having lived near there for three years, I say no. It doesn’t get warm enough to swim in IMO until late June.

Last year’s water temperatures at a lighthouse outside Kiel Fjord. That’s in deep water of course - I expect the water at the beach will be a bit warmer. In this current graph, the blue line is the water temperature at the lighthouse, and the red line the water temperature at a maritime research institute in the city itself.

Acccording to these graphs, expect mean air temperatures of 7 °C at night/16 °C at day in May, 7 sunny hours/day and 9 rainy days/month.

“Warm enough to swim” is incredibly subjective.

One thing I would say is that sea-water is surprisingly cold in May. In the Irish Sea (similar latitude to Kiel) I would rather swim in November than May. However the lag may be less in the Baltic (smaller and shallower).