Scientists predicted earlier this year that 2023 would see record temperatures as a result of El Nio and man-made global warming. The hottest day in recorded history occurred on July 3, 2023.

The US National Weather Service (NWS) issued heat advisories on Thursday to more than 112 million people in 15 states, comprising nearly one-third of the US population.

The heat wave is expected to set new records in several places, including Phoenix, Arizona, and Las Vegas, Nevada. The fundamental cause of the heat is a high-pressure aloft system, commonly referred to as a heat dome, that is settling over the Southwest but will influence a far greater area of the United States.

The NWS has stated that in the Southwest, there is no end in sight for the heat wave. “Unfortunately, the long-term outlook for the [Southwest] region shows a continued heat wave through this weekend and into next week," the NWS said.
 
Almost all of Texas, California, Oklahoma, Louisiana, Missouri, Nevada, and Arizona have issued warnings. A heat advisory is also in effect for southern Florida.

Some troubling records are in danger of being broken. Phoenix is on course to surpass or tie its record of 18 consecutive days at or above 110 degrees Fahrenheit (43.3 degrees Celsius) and may also break 120F (48.8 degrees Celsius), only the fourth time since reliable records began in the 1920s.

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The city's all-time high of 122F (50C) is also on the verge of dropping. Meanwhile, Las Vegas may shatter its record of 117 degrees Fahrenheit (47.2 degrees Celsius), as the NWS cautions that the city is entering a stretch of "extreme" heat.

Death Valley, which is already the hottest site on Earth, is anticipated to achieve temperatures ranging from 129 to 132 degrees Fahrenheit (53.8 to 55.5 degrees Celsius). The area has the record for the hottest air on Earth, reaching 134.1F (56.7C) in 1913.

Residents of the Gulf states may be unhappy to learn that the ocean waters will provide no relief from the heat. This month, temperatures in the Gulf of Mexico have ranged from the mid-to-upper 90s. During this time of year, Gulf temperatures often hover in the 80s.

Heat waves are unlikely to become less common very soon. El Nio, the heating phase of the El Nio-Southern Oscillation (ENSO), is anticipated to last into the winter of 2024.

It is projected to push global temperatures into previously unseen levels when combined with man-made climate change. Scientists also expect that extreme El Nio and La Nina (the cooling phase of the ENSO) events will become more often in the twenty-first century, increasing from one every 20 years to one every decade.