Extreme heat in the U.S. has killed 27 people in the past week — and the toll is rising

A searing heat wave that has gripped much of the United States in recent days is suspected of killing at least 27 people in the last week, according to reports from state officials, medical examiners and news outlets.

The number, which is based on preliminary reports from California, Oregon and Arizona, is likely to grow as authorities assess the death toll of a heat wave that began last week, delivering record-breaking temperatures throughout the West and scorching East Coast cities. As of Wednesday, more than 135 million people across the Lower 48 were under heat alerts, many of which are expected to continue until the weekend.

Most of the deaths have been reported in California, where the heat broke daily records late last week in a handful of major cities, including San Jose, Fresno and Oakland. In Santa Clara County, which includes San Jose, Chief Medical Examiner Michelle Jordan said her office is investigating 14 cases where people appear to have died from heat-related causes.

Of those, Jordan said eight of the individuals who died were over the age of 65 and most were found in their homes. Two of the cases involved people who were homeless, and one person was living in transitional housing.

“What I do want to emphasize is these cases are still under investigation,” Jordan said, adding that more a definitive death toll would probably take days or weeks to complete. At this point, the number of fatalities is not alarmingly high for the region, she said, “but obviously we’re going to experience another heat wave that’s going to last for the next three days.”

Adding to California’s death toll, on Saturday, a motorcyclist died of heat exposure in Death Valley National Park, where the temperature climbed to 128 degrees. Also that day, a woman incarcerated at the Central California Women’s Facility died as temperatures in the Central valley, where the prison is located, reached 110 degrees. Although local authorities cast doubt on whether the woman’s death was due to the heat wave, her daughter told the Sacramento Bee that she had complained of extreme heat inside the prison for years. On Sunday, a 58-year-old Sacramento man died of heat stroke after he was taken to a hospital from his un-air-conditioned home.

Oregon appears to have suffered a string of fatalities tied to heat as the state baked under triple-digit temperatures for days.

On Wednesday morning, an official with the Oregon State Medical Examiner’s Office said the heat was suspected in eight deaths, including six in the Portland, Ore., area. Most of the dead were elderly, but also among them were two 33-year-old men, one who died in Multnomah County and another in Coos County. The office did not provide information about the circumstances of their deaths or the dates when they occurred.

The medical examiner in Jackson County reported an additional suspected heat death, according to Jefferson Public Radio, bringing the number of victims in Oregon to nine.

In Arizona, NPR affiliate station KJZZ reported that a 4-month-old baby girl died on July 5 after becoming unresponsive while on a boat with her family on Lake Havasu. A spokesperson for the Mohave County Sheriff’s Department told the station that the girl had suffered a heat-related illness.

Since July began, hundreds of heat records have been set in the United States, many in the West. Temperatures have been so high that some rescue helicopters have been unable to fly, since the air has become too thin for chopper blades to grab onto.

The heat waves have not spared the East Coast. Raleigh, N.C., hit an all-time high of 106 degrees on Friday. In Maryland, the state’s health department reported two deaths from heat-related causes during the week of June 30 to July 6.

The total number of deaths caused by the heat wave may remain unclear for a long time. And public health experts cautioned that official death tolls are most likely an undercount.

Although heat is the leading weather-driven cause of death in the United States — it kills more people than hurricanes, tornadoes and wildfires combined — researchers, medical examiners and clinicians are still wrestling with how to accurately count the dead. Deaths from heat aren’t always obvious; they are often missed, categorized instead as heart failure or other cardiovascular problems, even if heat was the trigger.

In several states where residents have boiled under extreme temperatures in recent days — including Washington state, North Carolina and South Carolina — officials said they had not received any information about heat-related deaths at this point. California’s public health department could not provide a statewide estimate of suspected heat-related deaths by the time of publication.

Federal data shows that deaths from heat in the United States have steadily increased in recent years, climbing to just over 2,300 in 2023. About 1,600 heat-related fatalities occurred in 2021, and there were approximately 1,700 in 2022.

Ashley Ward, director of the Heat Policy Innovation Hub at Duke University, said there are signs that reporting and classification of these deaths is improving. In the past, she said, it was very hard to capture public interest in the dangers of heat. But that is beginning to change.

“The extreme nature of the heat last summer and this summer has meant it’s in the forefront of everyone’s mind, including those in charge of classifying health outcomes and deaths,” Ward said. “Awareness plays a critical role in this equation.”