Dangerous summer heat is unfolding across sections of the US over the July 4th holiday weekend with more than 150 million people across 21 states facing record-breaking temperatures.

In San Francisco, the National Weather Service said, “It cannot be stressed enough that this is an exceptionally dangerous and lethal situation.” The weather service warned about the impact of temperatures in California, which are expected to be between 100 to 120 F (38 to 49 C), saying, “It may not seem so if you live near the coast, but an event of this scale, magnitude, and longevity will likely rival anything we’ve seen in the last 18 years for inland areas.”

The oppressive heat wave in the Western US is “extremely dangerous and potentially deadly,” according to a NWS warning. Heat advisories were in effect on Friday for Washington, Oregon, Arizona and Nevada, where triple-digit temperatures were forecast.

“Confidence is increasing that this potentially historic heat wave will last several days,” the Portland NWS warned, adding that the risk of heat-related illness will increase significantly.

In San Jose, California, a homeless man died Tuesday due to the extreme heat. The man was 69, according to information from the Santa Clara Medical Examiner’s Office. In a post on Twitter/X, Matt Mahan, the mayor of San Jose, touted the city’s “cooling centers” and said, “it’s not compassionate to leave people suffering in unmanaged, unsheltered and unsafe conditions.”

San Jose is among the most unequal cities in the US. Along with the other existential threats to society—such as the coronavirus pandemic or the danger of nuclear annihilation—the catastrophic impacts of climate change-fueled heat waves are rooted in the class divisions within capitalist society.

As the center of Silicon Valley, .001 percent of San Jose households have $100 billion in wealth. This is 12 times more than half of the entire population of 2 million people in the region. The number of homeless in the area is the fourth highest in the US and is estimated at approximately 10,000 people.

A 10-year-old boy also died in Arizona on Tuesday after experiencing a heat-related emergency while hiking with family in South Mountain Park and Preserve, according to the Phoenix Police Department.

Police identified the boy on Friday as Cortinez Logan, originally from Missouri, who was rescued on the trail by fire crews and a police helicopter where temperatures had reached 113 °F (45 °C), according to the NWS. Logan was airlifted to a local hospital in critical condition where he died due to a “medical event.”

The cities of San Rafael and Livermore in California hit all-time high temperatures on Wednesday, registering 100 and 110 °F (38 and 43 °C)  respectively. An all-time high of 124 °F (51 °C) was reached in Palm Springs on Friday, the National Weather Service confirmed.

Meanwhile, the unprecedented temperatures are contributing to fires including the Thompson Fire in Northern California which has grown to over 3,000 acres and destroyed numerous structures.

Forecasters from the National Oceanic and Atmospheric Administration (NOAA) said much of the West Coast, Southeast, Mid-Atlantic and Northeast would experience temperatures above 100 °F (38 °C).

The temperatures in 92 major US cities are expected to reach dangerous levels on Saturday and Sunday. The New York Times published a table that showed Saturday temperatures for New Orleans, Louisiana (109 °F); Baton Rouge, Louisiana (109 °F); Mobile, Alabama (109 °F); Jackson, Mississippi (99 °F); Hattiesburg, Mississippi (106 °F); Gilbert, Arizona (110 °F); Mesa, Arizona (109 °F); Houston, Texas (109 °F); Chesapeake, Virginia (109 °F); and Richmond, Virginia (106 °F).

The heat dome responsible for the extreme temperatures is forecast to reach near-record strength and remain stationary over California and the Southwestern United States for seven to 10 days.

The NWS urged people to stay hydrated, out of the sunlight and in buildings with sufficient air conditioning. However, it is estimated that 12 percent of households in the US do not have air conditioning, and this translates into approximately 39 million people without air conditioning. Furthermore, millions will have to continue to work in warehouses and factories without proper climate control or outdoors under the threat of heat stroke.

Along with the unprecedented heat wave and the fires in California, Southern Texas is facing the threat early next week of the remnants of Hurricane Beryl, which is expected to dump heavy rains on the region. The first hurricane of the season, Beryl made landfall in Mexico on Friday after it killed 11 people in the Caribbean earlier this week. Beryl rapidly developed into a Category 5 storm under the influence of extremely warm Atlantic Ocean water.

Studies show that heat domes such as the present one are becoming larger and more intense because of capitalist-driven climate change.

Climate change studies, including the one conducted by the US Environmental Protection Agency (EPA), show that heat wave frequency, duration, length and intensity have all increased significantly since the 1960s.

The month of June 2024 was already the hottest on record in many places. In areas where records were not broken, temperatures in June were in the top five of all time. The June heat wave was unusually early and long-lasting compared with typical previous patterns. July is now poised to do the same.