Transportation Secretary Sean Duffy said the Federal Aviation Administration needs two more days to fully recover from the significant flight disruptions that came over the weekend due to the massive winter storm that swept across the country.

In an interview Monday on CNBC’s “Squawk Box,” Duffy said the FAA is targeting Wednesday as the day it hopes flights will return to normal.

“This storm is unique,” Duffy said. “You get the ice and you get the snow and, on top of that, we have now a cold weather snap that comes after it. … So it makes it more challenging to navigate the ice that’s going over the last three days.”

Sunday marked the largest flight cancellation day since early 2020, when the Covid pandemic hit. Airlines canceled more than 15,000 U.S. flights over the weekend, according to flight tracking website FlightAware, as much of the country was covered in snow and ice.

Duffy said the “massive disruption” was continuing Monday as the U.S. Department of Transportation deals with the fallout of the storm, with more than 4,000 flight cancellations for the day and nearly 10,000 delays. Those disruptions come as the FAA focuses on salting and clearing runways while dealing with lower staffing because commuting is difficult for workers, Duffy added.

There were roughly 250 U.S. cancellations so far for Tuesday, according to FlightAware, a significant drop from the weekend.

“We’re going to have more capacity as we come back to a full running schedule,” Duffy said. “So you’ll expect more full planes, more full flights as you fly this week, just as people are going to their destinations. But again, Wednesday is our target date to get back to normal.”

Airlines routinely cancel flights ahead of a major storm to make sure that planes, passengers and crew don’t get stranded, which can make disruptions even worse after severe weather clears. January is a low season for travel, but the massive winter storm was affecting travel for hundreds of thousands of people.

Multiple air carriers, including American Airlines, Delta Air Lines, JetBlue Airways, Southwest Airlines and United Airlinessaid they are waiving cancellation fees for customers to rebook.

The winter storm cancellations come just weeks after parts of the Caribbean airspace were closed following the U.S. attacks in Venezuela.

— CNBC’s Leslie Josephs contributed to this report.