LOS ANGELES, United States, (AFP) – More than 80 million people awoke Sunday to excessive heat warnings or advisories across western and southern US states where relentless, record-breaking temperatures are baking large swaths of the country.

The National Weather Service (NWS) warned of “a widespread and oppressive heat wave” throughout much of the West across to the South, with sizzling temperatures carrying into the coming week raising health risks for millions.

“Widespread record-breaking high temperatures, as well as record-breaking warm daily minimums are expected in parts of the Southwest, along the western Gulf Coast, and in South Florida,” the NWS said in a Sunday morning report.

At a Texas construction site outside Houston, a 28-year-old worker who gave his name only as Juan struggled in the blazing heat.

“Just when I take a drink of water, I get dizzy, I want to vomit because of the heat,” he told AFP, saying it was crucial to stay hydrated.

Residents of the metropolis have been asked to conserve electricity from 2:00 pm to 10:00 pm Saturday through Monday, in an attempt to mitigate high demand.

Southern Californians, who saw thermometers peak at 105-110 degrees Fahrenheit (41-43 Celsius) on Saturday, face a second day of similarly brutal temperatures, with the mercury expected to top 115F (46C) in parts of California, Nevada and Arizona, the NWS said.

By Saturday afternoon, California’s famous Death Valley, one of the hottest places on Earth, had reached a life-threatening 124F (51C), with Sunday’s peak predicted to soar as high as 129F (54C).

And on Saturday the town of Idyllwild, east of Los Angeles and some 5,400 feet (1,645 meters) above sea level, blew past its previous record to reach 100F. Imperial, California, east of San Diego, tied its daily record of 116F.

The NWS has said heat is the leading weather-related killer in the United States and urged Americans to take the risk seriously.

“In total, from South Florida and the Gulf Coast to the Southwest, over 80 million people remain under either an Excessive Heat Warning or Heat Advisory as of early this morning,” according to the NWS.

Authorities have been sounding the alarm for days, advising people to avoid outdoor activities in the daytime and to avoid dehydration, which can quickly become fatal in such temperatures.

In Arizona, state capital Phoenix has recorded 16 straight days above 109F, as temperatures hit 118F Saturday afternoon and stayed above 90F (32C) overnight.

The city has organized volunteers to direct residents to cooling centers and distribute bottles of water and hats, but program head David Hondula told the local ABC station that its three-days-per-week schedule is “clearly… not enough.”