Hi,
I went in june/july and the weather was scorching(i think everywhere in the med was hot though).
Port aventura was open til 8pm, dont buy your tickets at the park because of the queue's, might be a good idea to get there early before it gets too hot, we tried to go the following evening when it was cooler but the queues were long (this was a saturday and sunday though).
Everything was open and was very lively, should be good as most people are still at school that time of year