More than 300 flights have been canceled at Newark Airport.
More than 2,600 flights were canceled and nearly 7,900 were delayed across the United States on Sunday, according to data from FlightAware.
Airports in the Northeast are seeing the most outages as thunderstorms hit the area throughout the day, according to the Federal Aviation Administration.
New Jersey's Newark Liberty International Airport saw the most significant cancellations, with 362 flights canceled and 337 flights delayed, according to FlightAware.
John F. Kennedy International Airport has 318 canceled flights and 426 delayed flights. In addition, 270 flights were canceled at LaGuardia Airport with 292 delays and 259 flights were canceled and 459 delays at Boston's Logan International Airport, FlightAware data shows.
JetBlue has a significant impact, with 27% (283) of flights canceled and 43% (445) delayed. Regional airline Republic Airways is also impacted with 32% (320) of flights canceled and 20% (201) delayed, according to FlightAware.
Regional airline Endeavor Air, a subsidiary of Delta, is seeing 26% (174) of flights canceled and 18% (122) of flights delayed.
“Slow-moving storms will cause delays this AM into early PM across the Northeast, Midwest, and Southeast,” the the FAA said on Twitter on Sunday.
In the Northeast, more than 56 million people were under a flood watch as heavy rain moved through Sunday morning, causing flash flooding in parts of Virginia, Pennsylvania and New Jersey.
ABC News' Julia Jacobo contributed to this report.
