Millions are preparing to hit the road and take to the skies for Thanksgiving, but stormy weather is threatening to put a damper on travel plans.

Meteorologists are predicting a “significant storm” could bring rain, snow, wind, and even ice to large parts of the country ahead of the November holiday, according to AccuWeather. The storm is expected to impact travel in the Midwest from Monday to Tuesday before moving to the Northeast on Tuesday into Tuesday night.

On Monday, experts predict “severe thunderstorms” may be possible in parts of the South, according to The Weather Channel, followed by the potential for widespread rain, thunderstorms, and gusty winds in the central United States on Monday and Tuesday. That wet weather will then move east and locally heavy rain is possible across parts of the South and mid-Atlantic from Monday into Tuesday.

That stormy weather is likely to impact the more than 55 million Americans who plan to travel for the Thanksgiving holiday, one of the busiest Thanksgiving periods on record. Most of those will travel by car and must be aware of slick roads on highways across the country, according to AccuWeather.

“Motorists should expect some roads to become slippery, especially over the highest elevations in northern Pennsylvania and southern New York, but farther to the north from northern New York to northern New England, more general wintry driving is likely with accumulating snow,” AccuWeather Senior Meteorologist Adam Douty said.

However, millions will also plan to fly in what airlines have described as a record-breaking holiday for them. In fact, the Transportation Security Administration is predicting its busiest holiday season ever and expecting to screen a total of 30 million passengers through Tuesday, Nov. 28.

Bad weather always has the potential to lead to bad weather delays. Travelers planning to fly can check the Federal Aviation Administration’s color-coded flight delay information to see delays around the country in real time, and know your rights as a passenger (though weather-caused delays aren’t typically eligible for compensation).