A heat wave that has been sweltering the US Southwest for weeks is expected to move into the central and eastern United States.
By Wednesday, the hot weather will have moved eastward from the Midwest to the southernmost point of Florida, according to meteorologists.
Over the weekend, temperatures in several large cities broke records, and on Monday, extreme heat advisories were in effect for about 56 million Americans.
It is now anticipated that July will be the hottest month on record for the planet.
The city of Phoenix, Arizona, broke the previous record of 18 days set in 1974 on Sunday by extending its run of days with temperatures above 43C (110F) into a 24th day.
Since April, there have been at least 18 heat-related fatalities in Maricopa County's vicinity, and 69 additional deaths are being investigated.
Meanwhile, El Paso, Texas, a border town, saw temperatures above 38C (100F) for the 38th day in a row.
At least four deaths among guests at National Park Service parks in the southwest have also been reported.
In the midst of temperatures as high as 45C (114F), two female hikers were discovered dead on Sunday in Nevada's Valley of Fire State Park. Their identities and potential causes of death have not yet been made public by the police.
As the heatwave moves further east in the coming days, ocean temperatures in South Florida and the Keys may reach previously unheard-of heights. .
According to BBC Weather, a "heat dome," a sizable area of high pressure, is to blame for the heatwave.
Air is heated from the surface and held in place within this dome by hot air that is sinking from above.
According to BBC Weather meteorologist Simon King, "through this week, the heat dome will expand, bringing hotter weather and above average temperatures to pretty much the entire continental US.". .
This most recent heatwave will continue for another two weeks, according to the Climate Prediction Center of the National Weather Service.
The US has set or tied more than 13,000 high temperature records this year, as well as 16,000 low temperature records, according to data from the National Oceanic and Atmospheric Administration.
According to experts, heatwaves have increased in frequency, intensity, and duration as a result of human-induced climate change.
The Democratic governor of Washington State, Jay Inslee, told ABC News on Sunday that the heatwaves happening all over the world are proof that "the Earth is screaming at us.".
"The climate change bomb has gone off, the fuse has been burning for decades," he said.
"This is the new age, according to the scientists. The age of consequences has arrived.