Things to know about heat deaths as a dangerously hot summer shapes up in the western US

PHOENIX — A dangerously hot summer is approaching in the western United States. The heat is suspected of being the cause of dozens of recent deaths, including retirees in Oregon, a motorcyclist in Death Valley, California, and a 10-year-old boy who fainted while hiking with his family on a trail in Phoenix.

Heat is the leading cause of weather-related deaths across the country. But because investigations into suspected heat deaths can take months, and a hodgepodge of methods is used by provinces to count them, but it is not known exactly how many people died during the recent heat wave that started on July 1.

There are indications that these were two particularly deadly weeks.

“This is just a harbinger of what’s to come,” Joellen Russell, a climate scientist at the University of Arizona in Tucson, said Friday. “The floods, the droughts, the wildfires, the heat waves, the hurricanes, the thunderstorms — we’ve triggered all of these extreme weather events with the extra carbon dioxide that we’re putting into the atmosphere.”

Here are some things you should know:

Nineteen deaths are under investigation for possible heat-related causes in Northern California’s Santa Clara County, where a heat wave this month pushed temperatures into the low triple digits. The coroner’s office reported that four of the deceased were homeless and nine were over the age of 65.

At least 16 people are believed to have died from record-high temperatures in Oregon, mostly in the Portland area.

There have been nine confirmed heat-related deaths this year in Clark County, Nevada, which includes Las Vegas, according to the county coroner’s office.

Several recent deaths under investigation in Arizona involved small children, including a 2-year-old girl who was left alone in a hot car outside Tucson and a 4-month-old baby who died after becoming ill on a boat on Lake Havasu.

This month, records for high temperatures were broken across the western states, with Palm Springs, California, reaching its highest temperature ever. highest ever of 124 Fahrenheit (51.1 Celsius) on July 5 and Las Vegas recorded its highest point ever of 120 F (48.8 C) on July 7.

Las Vegas baked a record seven consecutive days of 115 degrees Fahrenheit (46.1 degrees Celsius) or higher during the recent heat wave, nearly doubling the old record of four straight days set in July 2005, the National Weather Service said. The city has seen at least 18 heat records since June 1.

In Death Valley, California, a high of 129°F (53.8°C) was recorded on July 7, tying the daily record set in 2007, the National Weather Service said. In Phoenix, it reached 115°F (46.1°C) on Wednesday, tying the record of 115°F (46.1°C). daily record set in 1958 and 1934.

Portland, Oregon set new daily record temperatures for five days in a row through Tuesday, when it hit 104°F (40°C).

The toll from the scorching heat is unknown because of the different ways jurisdictions calculate such deaths. But some counties in the southwestern U.S. fare better than most parts of the county.

Pima CountyArizona’s second-most populous county and home to Tucson, began recording heat-related deaths in a new online dashboard last year. Maricopa CountyHome to Phoenix, America’s hottest big city, has been tracking heat-related deaths for years. Clark County, Nevada, home to Las Vegas, is now also identifying deaths where heat was a contributing factor.

But the counting of heat-related deaths in most jurisdictions is inconsistent. In some places, death investigations are conducted by a coroner, usually a doctor trained in forensic pathology. In other places, the coroner may be an elected sheriff, as in Orange County, California. In some small counties in Texas, a justice of the peace may determine the cause of death.

Even the Centers for Disease Control and Prevention’s figures are often years behind and give an incomplete picture because they rely on information from death certificates, which come from local, state, tribal and territorial databases.

An Associated Press analysis of CDC data this year found that the death certificates of more than 2,300 people who died in the U.S. last summer reported complications from extreme heatthe highest number in 45 years of records. Doctors, public health experts and meteorologists say this is only a fraction of the real number of victims.

Sometimes it can take months for pathologists to determine whether a death is heat-related.

Unlike suicide by hanging or murder by a gunshot to the head, heat-related death is not always easy to determine. It can take weeks, or even months, to determine whether heat was a factor.

There is a lot of uncertainty that investigators have to wade through when a body is found in a warm apartment days after a death. While it may have been very warm when the person was found, it is impossible to know how warm a home was when death occurred.

Toxicology tests can also take a long time to detect substance use, such as alcohol or drugs.

That delay meant that the Maricopa County Public Health Department was unable to release its final count of 645 heat-related deaths for 2023 until this spring. The deaths also included those where heat was a secondary factor, such as a heart attack caused by high temperatures.

The temperatures in Portland, Oregon, have cooled downbut it is expected to be slightly warmer over the weekend, with highs around 32 degrees Celsius. Temperatures will extend as far as Salem and Eugene.

The National Weather Service in Phoenix said an extreme heat warning had been issued prediction This will continue through Saturday, with highs reaching 111 F (43.8 C) before dropping below 110 F (43.3 C) on Sunday and next week.

After 10 days under a warning for extreme heatLas Vegas is expected to experience slightly cooler weather over the weekend. Still, highs next week are forecast to remain above normal, ranging from 110 to 112 F (43.3 to 44.4 C), the National Weather Service said.

And summer isn’t over yet.

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Associated Press journalists Rio Yamat in Las Vegas and Claire Rush in Portland, Oregon, contributed to this report.