Beach
Jastarnia beach
Jastarnia, Poland · sea 18.8 °C at its warmest, in August

Sea temperature month by month
4.3Jan
3.1Feb
3.1Mar
5.1Apr
9.2May
13.9Jun
17.4Jul
18.8Aug
16.4Sep
12.8Oct
9.1Nov
6.2Dec
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020.
Wikipedia has no article about this beach yet. It is on the atlas from its Wikidata record and its photograph.
Questions
How warm is the sea at Jastarnia beach?
The sea off Jastarnia beach averages 18.8 °C at its warmest, in August, and 3.1 °C at its coolest. These are monthly means from NOAA's OISST v2.1 satellite and buoy record for 1991 to 2020, sampled at the beach's own coordinates.
When can you swim at Jastarnia beach?
The sea here never averages 20 °C in any month, so swimming means cold water all year. Some people do it anyway.
Where is Jastarnia beach?
Jastarnia beach is on the coast of Jastarnia, Poland, at 54.7052, 18.6729. The map on this site flies straight to it.