About 250 flights in or out of Denver International Airport were canceled as of 2 p.m. Wednesday as a winter storm hit northern Colorado.

Over a dozen other states in the northern and northeast U.S. are also under winter weather alerts, according to the National Weather Service, causing more than 2,400 flight cancellations nationwide, flight-tracking data tracked by FlightAware shows.

In Denver, the 249 cancellations as of early afternoon were split roughly evenly between arrivals and departures, accounting for 13% of each. Southwest Airlines flights made up more than half, at 147 cancellations, or 30% of its schedule through Denver.

SkyWest, a regional operator for major airlines including United Express, had 68 cancellations, or 22% of its flights; mainline United flights had 15 cancellations, or 2%; and Delta had 10, or 14%, while the remainder were scattered among other airlines.

Another 480 flights through Denver were delayed as of 2 p.m, including 235 departures throughout the day.