Yes, Disneyland in California is fully transformed with Halloween decorations starting in early September (usually the first Friday of the month). The "Halloweentime" celebration is one of the resort's most popular seasons. Visitors will see the iconic "Giant Pumpkin" shaped like Mickey Mouse on Main Street, U.S.A., and hundreds of hand-carved jack-o'-lanterns in the shop windows. The theme extends beyond just decor; popular attractions receive seasonal overlays, most notably Haunted Mansion Holiday, which is taken over by The Nightmare Before Christmas characters, and Guardians of the Galaxy – Monsters After Dark at California Adventure. The "Main Street Pumpkin Festival" creates a warm, autumnal atmosphere with orange and yellow bunting draped across the Victorian buildings. While it might still be 90°F in Southern California, the park leans heavily into the spooky spirit, making September an ideal time for fans of the holiday to visit before the massive October crowds arrive.