Nearly 44 million people are traveling this Memorial Day weekend, but severe spring weather threatens to disrupt some festivities with showers and thunderstorms forecast across the country, along with scorching heat in South Texas and Florida.

The summer travel season is already off to a busy start, with nearly 3 million people screened Thursday at Transportation Security Administration (TSA) checkpoints—the second-highest screening volume in the agency's history. The busiest airports so far include Atlanta, Dallas, Denver, Chicago, and Los Angeles.

The Federal Aviation Administration (FAA) reported last week that it is anticipating Memorial Day weekend to be the busiest since 2010, with 53,515 flights on Thursday and 50,129 on Friday.

However, travelers might face challenges as heavy rain and severe thunderstorms are expected to continue from the Midwest to the southern Plains on Friday, with extreme rainfall rates of up to 2 inches per hour. Forty-five million people are at risk from Chicago to Austin, Texas, with the biggest risks being damaging hail, strong wind gusts, and a few possible tornadoes. A severe thunderstorm watch has been issued for parts of Illinois, Iowa, and Wisconsin through 1 p.m. local time (2 p.m. ET), with threats of tornadoes and scattered wind gusts up to 75 mph. This means major airports in Chicago, St. Louis, and Dallas-Fort Worth could all see significant delays.

On Saturday, scattered storms are expected to move into the Northeast. Meanwhile, another round of severe weather is anticipated across the central and southern Plains before shifting into parts of the mid-Mississippi and Ohio valleys, according to the National Weather Service (NWS). Sixteen million people will be at risk of severe weather on Saturday, affecting Kansas, Oklahoma, and Missouri, with threats of strong tornadoes, hail, and winds over 75 mph likely, as well as nocturnal tornadoes in west-central Oklahoma and south-central Kansas. Cities to watch for storm damage include Oklahoma City, Kansas City, and Wichita.

Another outbreak of severe weather is possible on Sunday, with 39 million people at risk of strong tornadoes, damaging hail, and winds up to 75 mph. The cities with the greatest threat include St. Louis and Indianapolis.

Simultaneously, “dangerous and potentially record-breaking heat” continues across South Texas, the Gulf Coast, and southern Florida through Memorial Day, according to the NWS. Heat advisories are in place through 7 p.m. CT (8 p.m. ET) for parts of southern Texas, anticipating heat index values up to 114 degrees Fahrenheit.

On Memorial Day itself, the East Coast will experience rain and thunderstorms, the Midwest will see a mix of sunshine and rain, and the South will remain very hot and humid. Airports in Chicago, Detroit, New York-Newark, Philadelphia, and Washington are likely to face delays.

The weekend weather follows a week of wild conditions across the Midwest and South. Tornadoes have been reported every day since Sunday, with another 23 reported on Thursday.

Travelers are advised to monitor weather updates and plan accordingly, as the adverse weather conditions could lead to flight cancellations and delays. Road travelers should also be cautious, as heavy rain and thunderstorms could create hazardous driving conditions.

This holiday weekend, typically associated with the start of summer activities, may see significant disruptions due to the severe weather. Both local authorities and the National Weather Service are urging travelers to stay informed and take necessary precautions to ensure their safety.

Despite the weather challenges, the high volume of travelers indicates a strong desire for vacation and travel after years of pandemic-related restrictions. The transportation sector, including airlines and airports, is bracing for the increased demand while dealing with the potential impacts of severe weather.