Washington DC - Most of the US will experience hotter than normal weather throughout the summer, from July to September, a US government agency predicted Thursday, as a large part of the country sizzled in the first heat wave of the year.

"What we're predicting is generally that much of the US, excepting a few places, are forecast to be above normal," Johnna Infanti, a meteorologist for the National Oceanic and Atmospheric Administration (NOAA), told a press conference.

But the forecast does not offer any clues about possible extreme weather events during that time, she added.

The northeastern US is in the midst of a major heat wave just as summer officially gets underway.

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About 95 million Americans are under some kind of heat warning or advisory, according to the government-run website www.heat.gov. Soaring temperatures were expected to last until the weekend, the National Weather Service says.

"The early arrival of the heat in the summer season, persistence of heat over multiple days, and light winds and limited cloud cover will be aggravating factors in terms of overall heat stress," the NWS said. "Those without access to reliable air conditioning are urged to find a way to cool down."

On Wednesday, the small town of Caribou, Maine, tied its record high temperature of 96 degrees Fahrenheit. The mercury in New York and Washington rocketed into the high 80s and low 90s Thursday, with more heat to come.

President Joe Biden was briefed on the extreme heat, as well as the impact of Tropical Storm Alberto in Texas and New Mexico, and wildfires in the western US, the White House said.

Last year was the hottest year on record, and according to NOAA, 2024 has a 50% chance of topping that mark and will certainly be among the five hottest years ever recorded.

Human-caused climate change is heating up the planet at an alarming rate, sparking repeated intense heat waves, the global scientific community agrees.

According to experts at the World Weather Attribution (WWA), deadly heat that blanketed the US, Mexico, and Central America in late May and early June was made 35 times more likely due to global warming.