It's more of a question of preference. A little cooler than your body temperature (98.6° Fahrenheit) should not be too cold so that you don't get chilled. 70° to 78° Fahrenheit is the range where most folks feel comfortable swimming.
People Also Ask
There's no real optimal temperature, but many people feel “comfortable” swimming in water that is 70° to 78° Fahrenheit.
Close-in ocean temp is currently low 60's. If you happen to have a Southerly or westerly breeze, 65 can be very pleasant on the beach. If it's a northerly wind or one coming off the water, the actual temp on the beach will be much closer to the water temp, regardless of the reported air temperature.
Opt for a long-sleeve tee or layer on a lightweight button-up shirt when the temperature is hovering in the low 70s on a cloudy day. Be sure to pack a sweatshirt and breathable, moisture-wicking shorts to toss on for your morning beach walk or late at night as you curl up in front of the campfire to toast marshmallows.
The average temperature in Europe is 21.8°C. The highest current temperature on the continent according to our data, is in Koper (Slovenia) where water has 28.9 degrees celsius. On the other hand the lowest temperature is in Dalatangi (Iceland) where water has 12.1 degrees celsius.
Water takes a lot more energy to heat up and cool down than land does. Because of this, our summers are always cooler right at the beaches, and our winters are typically warmer.