Opportunities for Swimming in the Adriatic Sea

Last year the high was never over 72 for that time period.

https://www.timeanddate.com/weather/@3197708/historic?month=10&year=2024

What do you consider 'swimming' weather?

" The information I found leads me to believe the Adriatic Sea would be best to just look at not swim in"

That would be my conclusion.

But just how much room does it take ?
https://playback.fm/charts/top-100-songs/video/1960/Brian-Hyland-Itsy-Bitsy-Teeny-Weeny-Yellow-Polka-Dot-Bikini

I just returned from swimming in Croatia two days ago. Air temperature was "okay" water was cool. In 2 weeks its probably going to be very marginal. October is really late for beach vacations but maybe not for other activities in the region. I would return to Montenegro and Bosnia in October (actually been to both on October) in a heartbeat.

I would decide the day before, only a ten day forecast is going to have any value, and a swim suit takes no space really.
The sea is slow to warm (in May it has always been frigid) but it may be slow to cool also--I would consider midOctober to have a slight chance. Swim suits are also optional in many parts of Croatia, lol.

I just looked at my pictures from October 1-6, 2023 on Korčula and in Dubrovnik. We are swimming both places and wearing sleeveless dresses and the men shorts.
Mr. E - Preko is further north so a bit cooler in October.

We did that tour last September. Many from our group went swimming at Korčula but neither the air or water temps were warm enough for me to get in the water. Unless you have a burning desire to swim in the Adriatic Sea, I would say you could leave the suit at home.