Halloween Horror Nights 2025 starts on different dates depending on the location:

• Universal Studios Hollywood's Halloween Horror Nights 2025 starts on September 4, 2025, and runs on select nights through November 2, 2025.

• Universal Studios Florida's Halloween Horror Nights 2025 begins earlier on August 29, 2025, and also continues on select nights until November 2, 2025.

• Universal Studios Singapore Halloween Horror Nights 2025 runs from September 26 to November 1, 2025.

So the start date depends on the park, with Orlando starting in late August, Hollywood in early September, and Singapore in late September.