Trenton, New Jersey - A brutal heat wave over the Midwest and Atlantic coast has been linked to at least 19 deaths in the state of New Jersey, officials said.

"We are now up to 19 suspected heat-related deaths across the state," New Jersey Health Commissioner Raynard Washington told a press conference Saturday.

"Unfortunately, many of these individuals were found in homes without air conditioning, a few were outside their residences, some on the street and some even in parked cars," he added.

The National Weather Service said around 160 million Americans were under either major or extreme heat warnings as the country celebrated the Fourth of July holiday this weekend.

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Authorities urged people to stay indoors, check on their neighbors, drink more water than usual, and to find air conditioning if they don't have access at home.

"This weather is extreme and dangerous...and this is the hottest stretch we've seen in over 14 years," New Jersey Governor Mikie Sherrill warned residents.

More frequent, longer-lasting and more intense heat waves are one of the clearest signs of climate change, with Europe also recently hard hit.

Global average surface temperatures have risen roughly 2.5F above pre-industrial averages as a result of human-caused climate change, mainly driven by the burning of fossil fuels.

This week's "heat dome" conditions occur when high-pressure systems trap warm air like the lid on a pot.