A massive winter storm stretching over 1,500 miles from the Southern Plains to the East Coast has left hundreds of thousands of Americans without power and triggered record flight cancellations.

According to data from poweroutage.us, more than 730,000 customers in eight states—including Tennessee, Texas, and Mississippi—are experiencing outages as the storm intensifies. The system is expected to move into the Northeast by Sunday night, bringing 1 to 2 feet of snow across Washington, D.C., New York City, and Boston.

Flight cancellations have reached unprecedented levels, with airlines canceling over 10,000 U.S. flights for Sunday—a record for a single day since the start of the COVID-19 pandemic and more than double Saturday’s total. Over 1,800 additional flights are scheduled to be canceled for Monday.

The National Weather Service warns that extremely cold air will follow, extending hazardous travel conditions into next week. Severe thunderstorms may also produce damaging winds and tornadoes across the eastern Gulf Coast states this Sunday.