Theme parks reported reaching full capacity on Saturday after sunshine and unseasonably mild weather hit the UK.
By the afternoon, Drayton Manor asked people not to visit unless they had pre-booked admission.
Chessington World of Adventures said that people should only travel to the park via public transport, after its car parks reached capacity.
Both parks are operating a limited lineup of attractions for February half-term, ahead of their main seasons beginning next month.
Car parks at Southend-on-Sea also reached capacity, as thousands descended on the Essex town, which is home to the Adventure Island amusement park.
Blackpool Pleasure Beach extended its opening by an hour to 6pm, with admissions reported to have exceeded 10,000 people.
The Icon rollercoaster was running at three-train, full capacity operation after last week’s reliability problems during the park’s opening weekend.
More mild weather and sunshine is again expected across the UK on Sunday.