Travelers are heading to the airports in droves this Thanksgiving, but they may need to pack their patience thanks to a combination of bad weather and air traffic controller shortages.

Millions of Americans are set to hit the skies over the Thanksgiving holiday period in record numbers, but wet or snowy weather from the Rockies to the Midwest and the Northeast may slow things down.

A cross-country storm is expected go from dropping multiple feet of snow in California’s Sierra Nevada to then hitting the Denver area where it could dump up to a few inches, according to AccuWeather. The storm was then forecast to move East, gathering more moisture along the way and gaining strength from Wednesday night into Thursday night, resulting in moderate to heavy snowfall over northern New England and the higher elevations in central New England. The storm is also predicted to make for a rainy Thanksgiving Day parade in New York City. 

The South won’t escape the wet weather either, with AccuWeather warning of “locally severe thunderstorms from Louisiana, Mississippi and Alabama on Wednesday night to Georgia and South Carolina on Thursday.”

“We are tracking a storm moving ashore in Northern California into Tuesday that will have rainy and snowy implications in the East two days later,” AccuWeather’s Chief On-Air Meteorologist Bernie Rayno said in the report. “There are many variables we are still analyzing with this storm with track and intensity being the keys to where the rain and snow line will set up and the amount of snow that will fall in the Midwest and Northeast.”

Beyond weather, shortages in air traffic controllers in the Northeast threaten to wreak havoc ahead of Turkey Day. Newark Liberty International Airport (EWR) warned travelers may experience delays “due to FAA staffing issues,” and recommended they check their flight status and get to the airport extra early.

The Federal Aviation Administration (FAA) has been dealing with an ongoing air traffic control staff shortage for years.

No major delays had been reported out of the airport as of Tuesday morning, according to flight tracker FlightAware.

Elsewhere in New York, the Port Authority of New York and New Jersey warned travelers headed to John F. Kennedy International Airport (JFK) to avoid driving directly to the terminals if possible due to an ongoing major construction project. Overall, an estimated 1.34 million travelers are expected to head to the airport between Nov. 25 and Dec. 2, the agency told Travel + Leisure. 

“We would like our customers to spend as much time as possible with family and friends on this Thanksgiving holiday and as little time sitting in construction-related traffic at JFK,” Port Authority Chairman Kevin O’Toole said in a statement shared with T+L. “Leave extra time, use public transportation, pre-book parking if you absolutely have to drive to JFK and visit our website for the latest travel advisories before you leave for the airport.”