Beach
Sisters Beach
Tasmania, Australia · sea 18.2 °C at its warmest, in February

Sea temperature month by month
17.3Jan
18.2Feb
18Mar
16.7Apr
15.2May
13.7Jun
12.4Jul
11.7Aug
11.9Sep
12.7Oct
14.1Nov
15.8Dec
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 Sisters Beach?
The sea off Sisters Beach averages 18.2 °C at its warmest, in February, and 11.7 °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 Sisters 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 Sisters Beach?
Sisters Beach is on the coast of Tasmania, Australia, at -40.9100, 145.5600. The map on this site flies straight to it.