The witching hour belonged to the wizards, at least so far as the US box office was concerned. Harry Potter and the Half-Blood Prince opened in American cinemas at the ungodly time of 12.01am Wednesday morning. By sunrise it had earned an unprecedented $22.2m (£13.5m) from 3,033 screenings.

The figure breaks the previous $18m record for midnight screenings, set last year by The Dark Knight. It also eclipses the $12m midnight-run haul for the previous Potter outing, 2007's Harry Potter and the Order of the Phoenix. Variety claims that the bumper takings may be largely thanks to an older teenaged audience. The children who grew up on the JK Rowling source novels, it suggests, are now old enough to attend late-night film screenings.

Harry Potter and the Half-Blood Prince follows the adventures of our trio of adolescent wizards as their lengthy battle with the Dark Lord Voldemort enters the final straight. The last Rowling novel, Harry Potter and the Deathly Hallows, will be broken into two films which will be released separately in 2010 and 2011.

Emboldened by those midnight figures, industry experts now predict the latest instalment could earn as much as $150m during its five-day opening weekend in the US. Harry Potter and the Order of the Phoenix took $139.7 during the same period and went on to gross $938.2m at the global box office.