Several dozen flights at Hartsfield-Jackson Atlanta International Airport were canceled Sunday, and the issues may continue Monday.

Sixty flights were canceled and 154 flights were delayed by 3 p.m. Sunday, according to the tracking service FlightAware. That was well above the airport’s 2021 daily average of 10 flight cancellations.

More than 2,300 U.S. flights had been canceled by Sunday afternoon and another 4,279 were delayed, FlightAware reported.

Atlanta airport officials urged travelers to arrive early, at least 2½ hours beforehand Sunday and Monday because of increased expected wait times due to the high passenger volume, potential weather issues and staffing issues.

The National Weather Service put in place a winter weather advisory beginning at midnight through 9 a.m. Monday for portions of North Georgia. A mix of rain and snow could bring up to 2 inches of snow in far North Georgia.

Many airlines began blaming staffing shortages on increasing COVID-19 infections among crews just before Christmas.

Atlanta-based Delta Air Lines scrubbed more than 160 flights, according to FlightAware. The number of flights Delta canceled in Atlanta was not immediately available.

Southwest, the second-largest carrier in Atlanta, had canceled more than 410 flights in the U.S., or 11% of its schedule.

Before the holiday travel woes began, Hartsfield-Jackson International Airport officials said they expected to handle about 3.7 million passengers between Dec. 20 and Jan. 4. That is up from 2020, and on par with pre-pandemic levels.