ATLANTA -- Thanksgiving travelers found some flights delayed at Hartsfield-Jackson International Airport by fog, rain and a threat of snow flurries Sunday night.

On one of the busiest travel days of the year, the Federal Aviation Administration reported arrival delays of about one and a half hours for some flights because of rain, clouds and low visibility in Atlanta and other cities.

The FAA says departure delays have ranged from 10 minutes to about 45 minutes, depending on the destination.

However, the busiest single period of the holiday weekend will occur between 7 and 11 a.m. Monday, Hartsfield-Jackson spokesman John Kennedy told the Atlanta Journal-Constitution.

That block of time will see the last of the holiday travelers cross paths with business travelers.

Airport officials urged travelers to do their homework -- checking flight status, security waits and available parking -- before getting to the airport.