• Posted March 23, 2026

Heat Advisories Might Not Trigger Soon Enough For Some Seniors, Study Finds

Heat waves might endanger some urban-dwelling seniors at temperatures lower than those now used by cities to declare a heat emergency, a new study warns.

The risk of heat stroke and death among some seniors rises dramatically when the heat index reaches 90 degrees or higher for at least two days in a row, researchers reported March 20 in JAMA Network Open.

Currently, New York City issues heat alerts and open cooling centers when the heat index reaches 95 degrees Fahrenheit or higher for two straight days, or 100 degrees or higher for any length of time, researchers noted.

“We now know that emergency department use among vulnerable older patients spikes at around 90 F as opposed to 95 F,” said senior researcher Dr. Alexander Azan, an assistant professor of population health at the NYU Grossman School of Medicine in New York City.

“With an already severe heatwave underway in Western regions of the United States, now is the time for health care systems to prepare,” Azan added in a news release.

Nationwide, heat-related deaths have increased by nearly 17% a year since 2016.

To get a better idea of the riskiest temperatures, researchers tracked patients 65 and older treated at two New York City emergency departments during the summers of 2022 through 2024.

Overall, there were 55,200 visits at the two ERs, representing nearly 15,100 unique patients at one ER and nearly 19,600 at the other.

The first ER serves a socioeconomically, racially and ethnically diverse patient population, with a proportion of Medicaid-covered patients twice that of the second ER, researchers said.

Meanwhile, the second ER is at a larger academic medical center and tends to serve a greater share of higher-income patients.

Researchers compared ER visits to daily heat index data, which takes into account both the temperature and the relative humidity to calculate how hot it really feels like at any given time of day.

At the first ER, the risk of heat-associated emergencies among seniors began rising at 66 degrees, with risks running highest between 90 and 101 degrees.

Heat alerts issued at 90 degree days – versus 95 degree days – could have prevented about 116 ER visits during the study period, researchers estimated.

However, researchers noted that they found no significant association at the second ER – which serves more white, privately insured patients – between heat and health emergencies.

This indicates that effective heat warnings might need to be tweaked on a neighborhood level based on the communities served by individual hospitals, if they’re to help ward off heat-related illness and death, researchers said.

“Our hope is that other health care systems will leverage their own electronic health record data to identify the heat thresholds at which their patients are most at risk and target interventions appropriately,” Azan said.

Technology makes such customized warnings possible.

“By leveraging electronic health record data, health care systems can customize heat warning interventions to save lives and improve health during extreme heat events,” study co-author Dr. Leora Horwitz said in a news release. She’s director of the Center for Healthcare Innovation and Delivery Science at NYU Langone.

Researchers next plan to comprehensively review how social inequities might further add to the risk of heat-related illness in older adults.

More information

The U.S. Centers for Disease Control and Prevention has more on heat and older adults.

SOURCE: NYU Langone, news release, March 20, 2026