swimming in Salema, Portugal in JUne?

it would be definitely swimmable.

https://www.seatemperature.org/europe/portugal/lagos-june.htm
This link is for Lagos, but I am sure similar enough

A few people do swim briefly, but the sea there is the Atlantic not the Med and I find it too cold to swim at any time of year. If you are there early June, the sea won't have had much chance to warm up. The surfers wear wetsuits. I was in Salema a couple of years ago in early / mid July and the sea was so cold that it numbed my feet.

The sea is much warmer at the eastern end of the Algarve, close to the Spanish border.

All depends on what you are used to.
I swim in MA in the ocean starting in early July and through Sept. ; so confident June in Salema would be warm enough for me to swim.
Based on the temps on the link I sent though, definitely don't expect bath warm water.

Thank you, MReynolds and Jennifer,

I really appreciate your responses. Yes, much has to do with personal comfort levels. However, ocean temperature is ocean temperature. 64, 65, 66 is generally too cold for me. I can usually dunk into the water at 68 but not stay very long. 70 degrees and above is fine for me.

Thanks,
again,
alan