Credit: Michael L. Levitt/AP Photo/LAT

Indy 500 race fans today will endure record-breaking heat, with temperatures expected to exceed the mid-90's, as harsh weather upsets Memorial Day weekend plans across the U.S.

Doctors are on standby at 15 first aid stations set up at the race in Indianapolis. There are also 78 misting stations and even cooling buses so people can take breaks in an air conditioned environment. Doctors expect to treat at least 1,200 people. Fans are encouraged to drink lots of water and go easy on beer and caffeinated drinks.

The heat wave is expected to hit about half the nation today, from Washington D.C. to Texas to Massachusetts.  As many as 27 states could hit record-breaking temperatures today. Some highs in parts of the Midwest are expected to climb close to 100 degrees.

As people flock to the beaches this Memorial Day weekend, swimmers are warned to be wary of dangerous rip currents caused by sub-tropical storm Beryl, which led to at least 100 rescues Saturday.

"I couldn't move anywhere. Like I felt like I was in a concrete shell," said Rhyki Puma, who was swimming at Daytona Beach.

Credit: Matt Born, The Star-News/AP Photo

The Atlantic coast, from central Florida to southern South Carolina, could be hit with several inches of rain today as Beryl approaches the coastline. The storm is expected to make landfall tonight or Monday morning.

Jacksonville, Fla., Mayor Alvin Brown encouraged everyone to stay out of the water and indoors.

"This storm has the ability to do produce localized flooding, downed trees and downed power lines that can pose a threat to public safety," Brown said.

"There are no mandatory evacuations. However, we are encouraging residents living in low lying areas on boats to consider seeking shelter," he added.

In addition to scorching temperatures and rough waters, wildfires are spreading through 11 states.  The Michigan governor declared a state of emergency there, where an uncontained wildfires has burned more than 21,000 acres  so far.

ABC News Radio contributed to this report.