Last year was the hottest yet recorded around the world and in Santa Clara County, 38 deaths were determined to be heat-related because several heat waves brought daily high temperatures in San Jose above 100 degrees Fahrenheit in July and October.

On July 6, three deaths were attributed to extreme heat in the county. Overall, the death toll from last year’s heat is a massive increase from the 13 total heat-related deaths reported in the county over the previous six years.

Of those 2024 heat-related deaths, 27 were in San Jose, three in Mountain View, two in Milpitas and one each in Gilroy, Los Altos, Morgan Hill, Palo Alto, Santa Clara and Sunnyvale, according to data from the Santa Clara County Medical Examiner-Coroner’s Office. There also were two heat-related deaths in Alameda County last year.

San Mateo County did not identify any heat-related deaths in 2024 or in the preceding years, but did report 3 heat-related deaths in 2017 when a September heat wave killed over a dozen people.

“In the last couple years, we’ve seen the most extreme heats on record,” said Dr. Grant Lipman, an emergency room physician with Santa Clara Valley Healthcare. “And with these heat events, we’re certainly seeing a lot of heat illness in the emergency room.”

Lipman, who has done research on heat illness, said some groups are more at risk: homeless people, those who work outside, the very old and the very young.

Lipman said his research has shown that one of the best ways to cool someone down is cold-water immersion.

“We put them in a body bag; we fill it with ice,” Lipman said, describing the method he has used. “In about 10 minutes, we drop their temperature, we dry them off, zip up the bag and throw it out.”

Now, as spring showers and April flowers turn to hotter and longer days around the Bay Area, Lipman said people should remember to drink water when they are thirsty, to replenish electrolytes with salty snacks and get out of the sun if they feel overheated.

“The No. 1 diagnostic warning signal is if someone is confused,” Lipman said of when to seek medical care.

When people cannot or do not follow those precautions, their heat illness can become deadly and it is an increasing concern as extreme heat events become more common because of climate change.

On July 3 last year, as temperatures topped 100 Fahrenheit degrees in San Jose, California Insurance Commissioner Ricardo Lara released an analysis of the hidden costs of extreme heat in the state. The report found that between the seven extreme heat events they investigated, it cost an estimated $7.7 billion to government and industry.

“Extreme heat is a silent, escalating disaster that threatens our health, economy, and way of life in California,” Lara said when the report was released.

The medical examiner’s office announced that they were investigating 19 deaths as possibly heat-related in July, but it can take weeks or months for death investigations to be completed. They determined that 21 deaths in the county in July were heat-related.

“The Office of the Medical Examiner evaluates a variety of factors when determining whether fatalities are caused by heat,” a spokesperson said in an email.