A historically hot summer is on a killing spree and it shows no signs of stopping

A historically hot summer in the United States is on a July killing spree and the toll will only grow with the hottest days yet to come.

It’s been the hottest summer on record to date for around 100 US cities from Maine to California. Heat is suspected in the deaths of least 37 people in the US in July, a number that is likely underestimated given the amount of time it takes to attribute a death to nature’s most prolific weather killer.

Many of the deaths have been in the West, where cities have shattered all-time record high temperatures during an unprecedented and long heat wave – exactly the kind of conditions scientists expect in a world warming due to fossil fuel pollution.

Heat is being investigated in the deaths of at least 19 people in Santa Clara County, California, alone, the county’s medical examiner office told CNN.

Everyone is vulnerable to heat, but some are more at risk than others. Children, the elderly, pregnant people, people with heart or blood pressure issues, outdoor workers or anyone without access to reliable cooling are more likely to succumb to heat-related illnesses than others.

At least three of the people who may have succumbed to heat in Santa Clara County were unhoused without adequate access to cooling. Nine were over the age of 65, the county medical examiner told CNN.

At least one person died from heat in Southeast Texas, where more than 1 million people are still without power for the fourth day after Hurricane Beryl. Others have died or been sickened trying to keep cool improperly using generators.

At least four children – a 2-year-old in Arizona; a 2-year-old in Georgia; a 4-year-old in Texas; a 5-year-old in Nebraska – died after being left in cars during this month’s heat.

Another child – a 10-year-old – died of a “heat-related medical event” while hiking in a Phoenix park amid searing heat last week, according to the Phoenix Police Department. Phoenix has broken or tied multiple daily heat records since the start of July.

High temperatures have climbed above 110 degrees and lows have failed to fall below 90 in the city each day since last Tuesday. Dozens of other deaths are being investigated by Phoenix’s Maricopa County for potential heat-related causes.

At least 10 suspected heat deaths are being reported in Oregon. At least six have been in Portland’s Multnomah County. Portland smashed daily high records for at least five consecutive days in the past week, rising into the triple digits on three occasions.

The heat has also taken a toll on recreationalists attempting to enjoy the outdoors in hostile weather.

A motorcyclist died from heat exposure in Death Valley on Saturday. The high temperature topped out at 128 degrees, setting a daily record and coming within six degrees of the hottest temperature ever recorded on Earth.

A tourist hikes in the Mesquite Flat Sand Dunes in Death Valley National Park, near Furnace Creek, during a heatwave impacting Southern California on July 7, 2024. - Etienne Laurent/AFP/Getty Images
A tourist hikes in the Mesquite Flat Sand Dunes in Death Valley National Park, near Furnace Creek, during a heatwave impacting Southern California on July 7, 2024. - Etienne Laurent/AFP/Getty Images

A 50-year-old man also died while hiking on Sunday amid extreme heat in Grand Canyon National Park, the National Park Service confirmed.

Some of these deaths are still under investigation, since confirming heat as a cause of death has always been “a complicated process,” David S. Jones, a physician and historian at Harvard University, previously told CNN. A medical examiner or coroner must list a single cause of death, and in some places, those officials are political appointees or elected officials who may not have any kind of medical background.

“The (cause of death) assessment itself is a complicated one,” Jones added. “If someone is found deceased in an apartment, and you’re trying to figure out what was the top cause of death to list, many medical examiners will say, ‘well, the person must have died of heart disease in some way because their heart stopped.’”

Heat-related deaths will likely rise in the coming weeks as more are confirmed and temperatures stay high.

The extreme nature of the heat in the West will start to ease late this weekend, starting a slow return to near- or slightly above-normal summer heat. The region is still typically quite hot in July even without heat reaching record levels daily.

Heat will be a consistent companion over much of the US with hotter than average temperatures likely through the end of July and into at least early August, according to the Climate Prediction Center.

CNN Weather
CNN Weather

CNN’s Rachel Ramirez, Sara Smart, Jillian Sykes, Sarah Dewberry, Raja Razek, Chris Boyette, Jamiel Lynch, Cheri Mossburg and Amanda Musa contributed to this report.

For more CNN news and newsletters create an account at CNN.com