More than half of United States under heat and flood advisories

A dangerous heat wave will continue to affect the East Coast and the central plains of the US during the weekend, triggering the National Weather Service (NWS) to issue heat alerts for millions.

More than 190 million people, or 60% of the US population, have been under a heat advisory or flood warning since Thursday, according to the NWS.

The heat wave is hitting "all the big cities," said Bob Oravec, lead forecaster with the NWS's Weather Prediction Center. "That's why the population (affected) is so high."

For millions from coastal Virginia through Washington, D.C., and to Boston, Friday and Saturday are expected to be the hottest days of the summer.

The NWS issued an "Excessive Heat Warning" for New York City as of Thursday at 11 a.m. (local time) through Friday at 9 p.m., and said temperatures are predicted to reach the upper 90s (over 30 Celcius) with heat indices of 104 degrees (40 Celcius).

The head of the UN warned Thursday that ''the era of global boiling has arrived'' as July is set to be the hottest month ever recorded on Earth.

''Climate change is here. It is terrifying. And it is just the beginning. The era of global warming has ended; the era of global boiling has arrived,'' Antonio Guterres told reporters at the UN headquarters in New York.

US President Joe Biden announced a series of measures Thursday intended to help Americans cope, including asking the Labor Department to issue a heat hazard alert and step up enforcement of labor laws to protect workers. The alert is intended to remind employers that workers have federal heat-related protections, and the agency is slated to crack down on any violations.