Is it warm enough to swim in Dunedin NZ?

I may be studying abroad there, and was wondering if the beaches are ever warm enough to swim in..? I know since it very far south its usually cold, but I'd plan on going between Jan-May ( I believe this is your summer going into fall). I don't mind the cold, but I love the thought of swimming at the beach one day, and then snowboarding in the mountains another. I'm a very adventurous/active person, and I feel like Dunedin is the place where I could go to school and experience almost everything New Zealand has to offer. It's an absolute dream to go here, and I think the country is nothing but breathtakingly beautiful! I think I read that your warmest temp is around 70 Fahrenheit (I'm not sure what Celcius that is). thank you!