Walt Disney World operates 365 days a year. Opening and closing times vary by park and by season, with the longest hours during prime summer months and year-end holidays. The parking lots open at least an hour before the parks do.
In general, openings hover around 9 AM, though certain attractions might not start up till 10 or 11 AM. Closings range between 5 and 8 PM in the off season and between 8 and 10, 11, or even midnight in high season. Downtown Disney shops stay open as late as 11 PM in summer and during holidays.