Scorching heat will provide an endurance test for thousands of aspiring singing stars who have already registered for American Idol auditions for the Fox show's 12th season in Newark.

They started lining up early Thursday in front of the Prudential Center. Contestants can sign up 24 hours a day until Saturday morning when the auditions begin.  Producers allowed sign-ups to begin earlier than usual due to the heat.

Producers issued a warning for those who come to the Prudential Center to be prepared for the heat with water, hats, sunscreen and sunglasses.

The actual auditions will take place Saturday inside the arena. Once a contestant signs up they are not allowed to "hang around" the Prudential Center until the lineup to actually perform begins on Saturday morning.

Authorities say traffic in the area will be detoured through Saturday.

It's the second straight year that Newark is hosting auditions for a national singing competition. In April 2011, thousands turned out to audition for "X Factor."

Next month, live tapings for "America's Got Talent" will begin on July 2 at the New Jersey Performing Arts Center, several blocks from the arena.

This will be the 5th time American Idol has held auditions in New Jersey. Last season's auditions were a last minute addition held in September instead of the customary summertime which kept down the number of auditioner who would come from all over the northeast.

Last year's auditions in New Jersey did not get featured on its own night when "Idol" began the season. Instead, those who made it through the audition process were flown made a part of auditions in other cities.

The Associated Press contributed to this report.