Yes, both Walt Disney World and Disneyland are fully decorated and programmed for Halloween throughout the entire month of September. In fact, the spooky season typically begins as early as mid-August. At Magic Kingdom, you will find the park adorned with "Mickey's Pumpkin" wreaths, fall foliage, and themed bunting. September is also the primary month for Mickey’s Not-So-Scary Halloween Party, a separate-ticket event that occurs on select nights and features exclusive fireworks, a parade, and trick-or-treating. Over at Disneyland in California, "Oogie Boogie Bash" usually runs throughout September at Disney California Adventure, and popular attractions like Haunted Mansion receive their "Holiday" (Nightmare Before Christmas) overlay. While the weather in Florida and California remains very warm in September, the atmosphere is decidedly autumnal. For many travelers, September is considered a "sweet spot" to experience the Halloween festivities with slightly lower crowds than October, though it is important to check the calendar as the parks often close early to daytime guests on event nights.