Airlines have canceled hundreds of flights scheduled for Friday due to the winter storm expected to make travel hazardous due to snow and freezing rain.

At Hartsfield-Jackson International Airport, Delta’s largest hub, there were more than 420 flights canceled for Friday, according to FlightAware.com.

Atlanta-based Delta Air Lines canceled more than 160 of its flights scheduled for Friday, including Delta Connection regional carrier flights. That includes more than 115 flights in Atlanta, or more than 8% of its flights scheduled for the day at the world’s busiest airport, FlightAware data show.

The airline urged customers to check their flight status on its website or app.

Most parts of metro Atlanta could get up to a quarter-inch of ice, according to the National Weather Service, which issued a winter storm warning, in effect from 7 a.m. Friday to 7 a.m. Saturday. Gov. Brian Kemp issued a state of emergency ahead of the severe winter weather.

Delta CEO Ed Bastian told The Atlanta Journal-Constitution Thursday afternoon that the company didn’t “know anything different than you know” about the weather but that it’s prepared and will run a reduced schedule Friday. “There will be proactive cancellations and thinning, that’s what we always do in advance of a major event to keep customers out of the airport and try to give them as much notice in advance,” he said.

However, other airlines canceled flights earlier Thursday.

Southwest Airlines, the second-largest carrier at Hartsfield-Jackson, canceled more than 120 flights scheduled for Friday in Atlanta, according to FlightAware. That’s the majority of the flights Dallas-based Southwest had planned to operate in and out of Atlanta on Friday.

Frontier Airlines canceled nearly all of its flights scheduled at Hartsfield-Jackson for Friday. The ultra low-cost carrier canceled more than 70 of its Friday flights going to or from Atlanta, according to FlightAware.

Spirit Airlines canceled more than 30 of its Friday flights in Atlanta, more than half of its schedule for the day at Hartsfield-Jackson. United Airlines canceled more than 20 of its Atlanta flights, roughly half of what it had scheduled at Hartsfield-Jackson for Friday.

Delta said those whose flights are canceled will be automatically rebooked or can seek alternate flights by contacting Delta at the airport, by phone, or by messaging through the Fly Delta app.

Those whose flights are canceled or delayed by three hours or more for domestic flights can request to be rebooked, or if they choose not to fly they are entitled to a refund for a flight they did not take.

The Atlanta disruptions come after Winter Storm Cora already caused havoc in Dallas. Airlines canceled more than 1,600 flight cancellations at Dallas-Fort Worth International Airport and Dallas Love Field on Thursday.

Airlines on Wednesday warned of the travel disruptions and issued waivers to give travelers around the Southeast more flexibility to change their flight bookings in advance of the storm.