Hopefuls trying their luck will perform in front of producers and if they impress they'll sing for the judges later in the competition.
Returning host Dermot O'Leary who is in Cardiff for the auditions, said: "As always I'm looking forward to the laughs, the hugs, maybe not so much the tears, and watching really talented people... and some not-so-talented people.
"But that's the beauty of the show - you never know who's up next."
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A cold night but temperatures remain above zero
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Outbreaks of rain will continue through the night, turning heavy in places