Hello Maria,
The academic year ends around the start of July, so you usually have at least 6 weeks off in the summer. The year is broken up into 4 10-week quarters, with a short break in between those and a few other holidays thrown in the mix too.
The program is manageable if you stay focussed. I would advise trying to keep on top of your studies, prepare for each class with the recommended readings/tasks and you will be fine.
Hope that helps.