The hours the different theme parks (Magic Kingdom, Animal Kingdom, Epcot, and Hollywood Studios) are open during your Disney World vacation do deviate by time of year. In summertime and the winter holiday season, Magic Kingdom which is the most popular park usually stays open later up till 11:00 P.M. The other parks commonly close down a little earlier, so if Epcot, Animal Kingdom or Hollywood Studios are important parts of your planned vacation, remember to keep that in mind.
Now for the weather, if you plan to go in the summer months expect to run into very hot days, high humidity and a short downpoor in the afternoon. Many Disney World vacations vets swear that if you go in the summer you may prefer to consider going in the morning, calling for a break when the hot afternoon sun is out, then going back for a warm evening of amusement under the night lights of the park. As well as during the summertime, you should expect to come across the occasional rain storm. As long as your prepared, then a little rain should not spoil your enjoyment of Disney.