Life-threatening heat is returning to the West before spreading to the East Coast later this week.
This weekend, record highs were tied and broken from Florida to Colorado.
Dalhart, Texas, in the Texas Panhandle, hit a record high of 103 degrees, while Baton Rouge, Louisiana, reached a record 98 degrees.
Jacksonville, Florida, tied its record high of 99 degrees and Grand Junction, Colorado, tied its record high of 98.
The heat will linger in Florida for one more day Monday, with the temperature possibly reaching 100 degrees in Jacksonville.
On Tuesday, the heat will again move into the West with a heat dome taking over the Southwest.
By Wednesday, temperatures could climb to a dangerous 109 degrees in Las Vegas and 112 degrees in Phoenix.
The heat then moves east. By the end of the week, record highs will be possible from Massachusetts to North Carolina.
By Friday, the temperature is expected to jump to 90 degrees in New York and 96 degrees in Washington, D.C.
Doctors recommend taking excessive heat warnings seriously. There are hundreds of deaths each year in the U.S. due to excessive heat, according to CDC WONDER, an online database, and scientists caution that the actual number of heat-related deaths is likely higher.