President Joe Biden warned Americans traveling ahead of the Christmas holiday weekend to be careful and leave early if possible to avoid the massive storm expected to hit several states Thursday night.

“This is not like a snow day when you were a kid,” Biden said. “This is serious stuff.”

Biden was briefed by officials from the National Weather Service and FEMA in the Oval Office Thursday morning. Large swaths of the continental U.S. are under blizzard, ice storm and winter storm warnings. Other areas are under wind chill, freeze and flood warnings.

The National Weather Service website warns of a “widespread and dangerous arctic blast” approaching which will cause “life-threatening cold” and “consume much of the lower 48.” The Midwest and Great Lakes regions are expected to receive the bulk of the snow fall with nearly all of the Great Plains region under a wind chill warning. The storm will “produce widespread disruptive and potentially crippling impacts across the central and eastern United States.”

Airlines canceled more than 2,800 flights from Wednesday through Friday, according to tracking site FlightAware. That period includes what airlines expected to be the busiest travel times before Christmas, which is Sunday.

American, Southwest, United, Delta, Spirit, JetBlue, Alaska and other airlines issued weather waivers for dozens of destinations around the country, allowing travelers to change their departures without paying a change fee or difference in fare.

Regardless of how they plan to travel, Biden encouraged Americans to listen to guidance and be careful.

“I encourage everyone, everyone to please heed the local warnings,” Biden said, adding information can be found on weather.gov.

Biden said the White House has tried to contact governors of 26 states slated to be hit by the storm.

CNBC’s Leslie Josephs contributed to this article.