More than 600 flights were cancelled at O’Hare International Airport on Saturday morning ahead of a major winter storm expected to wallop the region with around 10 inches of snow.

According to the flight-tracking website FlightAware.com, 627 flights scheduled to arrive at or depart from O’Hare had been cancelled as of 9:45 a.m. In addition, 331 flight delays were reported.

Delays at the airport were averaging 37 minutes, the Chicago Department of Aviation said on its website.

Due to the snow and ice, the Federal Aviation Administration instated a ground delay at O’Hare, which was averaging five hours. Similarly, a ground stop was put in place for a period of the morning but had been lifted by 9:45 a.m.

The situation was better at Midway Airport, where 29% of flights had been canceled compared to O’Hare’s 46%. Midway reported 76 cancellations as of 9:50 a.m. and delays of under 15 minutes.

NBC Chicago’s Jenn Schanz was out on the roads Saturday morning, getting a first-hand look at weather conditions, ahead of a major winter storm.

The flight delays and cancellations come as officials urge travelers heading home from their Thanksgiving destinations to use caution, including on the roads.

Drivers should expect slick roadways, allow for extra time and be extra cautious, authorities said. To make sure you get to your destination safely when driving in snowy conditions, reduce speed, increase braking distances and allow more space between you and other vehicles.

“Think about whether driving is really necessary,” Illinois State Police Division of Patrol Col. Chris Owen said Friday. “Depending on the amount of snow and road conditions, if your vehicle becomes disabled, troopers can help you get to a safe place, but your vehicle will have to wait. Is it worth it?” 

The National Weather Service warned that drivers should consider delaying travel unless it’s “absolutely necessary,” with driving expected to be very difficult to impossible. Roads and bridges will likely be slick and dangerous, and strong winds along with the weight of snow on tree limbs could cause sporadic power outages.