Southwest canceled over 700 flights on Martin Luther King Day—and hundreds more the next day

Passengers on Southwest Airlines are facing an increasingly familiar travel hurdle, as the carrier was forced to cancel 786 flights Monday and, as of 9:30 a.m. ET, 336 today.

The travel disruptions come as a significant portion of the country is dealing with severe weather after a bomb cyclone brought dangerously cold weather across the Plains. The cancelations have nothing to do with technical issues, which were to blame for 2022’s infamous holiday travel meltdown for the carrier.

Many of Southwest’s routes are in cities that were impacted by the storm system, including Chicago and Denver.

On Monday, Southwest was forced to cancel 12% of its flights. So far on Tuesday, it has shut down 9% of its operations, according to FlightAware. The cancelations should ease as Tuesday continues, with the storm moving toward the east and temperatures start to climb.

While Southwest has led the industry for flight cancelations for three days now, it’s not the only airline that’s being impacted by weather conditions. United has cancelled 295 flights so far on Tuesday (12% of its total) and KLM has cancelled 167 (some 26% of its schedule). All totaled, there have been 2,398 cancellations so far on Tuesday, after more than 4,500 on Monday.

Over the same period, 43,173 flights saw delays.

The delays and cancellations follow an already rough week for the airline industry, following the grounding of all Boeing 737 Max 9 aircraft after a piece of the fuselage blew of an Alaska Airlines flight while it was 16,000 feet in the air.

United and Alaska Airlines are the two largest carriers that include the Max 9 in their fleet. Southwest does not fly any Max 9 planes.

This story was originally featured on Fortune.com