The meaning is ambiguous - do you mean 

1. "I will be able to (do the activity) swimming this summer (because I have no access to the pool now)? or

2. "I will become capable of swimming by the time summer arrives (because I don't know how to swim now and thus I'm currently training to swim)? 

For 1, it's 夏天到我就能夠去遊泳池游泳了。

For 2, it's 夏天到我就學會游泳了。

我这个夏天能游泳了

这个夏天我就能学游泳了。

be able to 能

这个夏天我就能学游泳了。

这个夏天我要学会游泳~