NASCAR canceled all Saturday track activity at Talladega Superspeedway because of threats of extended periods of severe weather.

Track officials said the decision was made on advice from the Talladega County Emergency Management Agency and the National Weather Service, which said Talladega County was one of the areas in Alabama facing a high risk of severe thunderstorms and tornadoes today.

"Fans are strongly encouraged to take necessary precautions to ensure their safety, especially those guests camping on speedway property," track officials said.

The Nationwide Series race scheduled for Saturday will now be held Sunday following the Sprint Cup Series race. It's the second consecutive weekend that NASCAR will attempt a doubleheader.

Rain last weekend in Texas washed out both Cup and Nationwide events, and they were run back-to-back on Monday. Drivers who competed in both series totaled 801 miles of racing.

There are 10 drivers scheduled to run both of Sunday's races, which are scheduled to total 811.30 miles barring any additional "overtime" laps.

Qualifying for Talladega's Cup race was canceled, and the field for Sunday's race will be set by owner points. Four-time defending champion Jimmie Johnson will lead Matt Kenseth and Greg Biffle to the green flag.

With the new schedule set, officials turned their attention to safety.

Fans camping on the sprawling speedway grounds were encouraged to dismantle their tents and seek more stable shelter. Most drivers and crew chiefs are also on property in their private motorhomes located just aside the garage. Security was going motorhome-to-motorhome to advise competitors of areas inside the track where they could seek shelter.

At least one driver, Denny Hamlin, left the property. Hamlin posted on his Twitter page he was headed back to Charlotte, N.C., to catch Game 3 in the NBA playoff series between the Bobcats and Orlando Magic.

Dale Earnhardt Jr., still on the clock as he and Jamie McMurray helped Daytona International Speedway announce a repaving project set to begin in July, said he didn't know what he'd do during the storms — particularly if there's a tornado.

"I was gonna ask for advice about the best plan," Earnhardt said. "I ain't got my plan together yet. I'll look up in the sky a lot, I reckon."

All tickets for either race will be honored Sunday, with seat priority given to those with tickets to the Cup race. Fans with tickets to the Nationwide event will be directed to the nearest open seat.

The Sprint Cup race will begin at 1 p.m. Eastern, as scheduled, and the Nationwide Series race will follow.