Maryland Breaks Heat-Related Death Record With Weeks of Summer to Go

Prolonged heatwaves pushed death tolls to new levels this year in Maryland, which recorded its highest number of heat-related deaths with more than a month left of summer. 

At least 70 deaths across the U.S. were linked to the heat domes that covered much of the country in July, according to an analysis by The Washington Post. July was the hottest month across the United States since the National Oceanic and Atmospheric Administration began keeping records 132 years ago. 

An August 2024 study that analyzed deaths occurring between 1999 and 2023 using data from the Centers for Disease Control and Prevention estimated a 117 percent increase in the number of heat-related deaths, totalling 21,518 during the reporting period. 

In Maryland, the toll has been especially stark this summer. 

As of Aug. 12, the state health department’s dashboard showed 52 Marylanders have died of heat-related causes since May, up from the 50 reported a week earlier. The latest count surpassed every full season shown in state data going back to 2021. Forty-five deaths occurred in July alone, more than the annual total in any of the previous five years. Older Marylanders accounted for the majority of the deaths, with people 65 and older representing 62 percent of the total. 

Geographically, the dashboard map shows the most reported deaths in Prince George’s County and Baltimore City, with several neighboring counties and jurisdictions also showing comparatively high numbers.

Maryland’s previous record for heat-related deaths—46 in 2012—was tied to a derecho event that knocked out power across much of Maryland for nearly a week during a heat wave. In contrast to that, this year’s fatalities happened with the grid intact. Experts say a regular hot summer is now doing what a catastrophic freak event previously did, landing the hardest on the state’s oldest and most-vulnerable residents.

Maryland’s summer is running measurably hotter than usual, said Alfredo Ruiz-Barradas, the state climatologist and an associate research professor in the University of Maryland’s Department of Atmospheric and Oceanic Science. 

He cautioned that he had not yet analyzed the full season, which runs from May to September, but shared the measurements his office tracks: hot days, when the high temperature tops 86 degrees, and heat waves of two or more such days in a row. 

Through the end of July, he said, the state recorded six more hot days and two more heat waves than normal, along with seven more “warm nights,” when the minimum temperature stays above 68 degrees, than a typical year.

Ruiz-Barradas said these temperatures may not seem extreme but they can have extreme effects on the people most exposed to them, such as those who work or live outdoors and “people without the luxury of AC.”

The early July heatwave was in a different category. Both daytime highs and overnight lows stayed above the measured thresholds “for more than a week, and even higher thresholds for 3 to 4 days,” he said. Most of the season’s deaths occurred during that stretch.

At least by one measure, Ruiz-Barradas noted, this July was not Maryland’s most extreme because the mean temperature last year was higher. Record temperature alone does not translate into a record death toll but rather depends on who is exposed and vulnerable to heat and for how long.

“Rising global temperatures have a local impact through increasing temperatures in the state, too, which are amplified by large cities like Baltimore,” he said, pointing to asphalt and concrete-rich built environments that trap heat and necessitate cooling measures. “So the trends are there and should be used for adaptation planning.”

Heat-related deaths are not limited to heat stroke, said Dr. Meredith McCormack, a professor of medicine and director of the Division of Pulmonary and Critical Care Medicine at Johns Hopkins University School of Medicine. 

The danger comes from the stress prolonged heat waves put on the whole body, she said, and the very young, the elderly and those with chronic illness are the hardest hit. “The human body is less able to adapt and respond during very early childhood and as we age into older adulthood,” she said in emailed comments, noting that heat also raises the risk for people with underlying heart and lung diseases and with diabetes.

Consecutive days of heat exposure and higher nighttime temperatures are especially harmful as the body has less time to recover,” McCormack said. And nighttime heat is becoming more common especially in cities, where materials retain heat and keep nighttime temperatures elevated. Households with limited or no air conditioning, she said, are most exposed when the heat runs day and night without a break.

Asked what would most reduce the toll, McCormack stressed access to air conditioning and limiting time vulnerable groups spend outside. She said barriers to air conditioning are largely financial, and programs that both provide cooling and help cover the cost of running it, she said, could protect several people in a single household at once. At the health-system level, she said, her team is developing ways to warn and guide vulnerable patients to limit time outdoors on the most dangerous days.

The Maryland Department of Health did not respond to the questions about the elevated deaths during regular summer and what the agency is doing differently to reach older and vulnerable residents.

“The increase we’ve seen in Maryland is part of a global trend,” said Benjamin Zaitchik, a professor in Johns Hopkins University’s Department of Earth and Planetary Sciences. “While disaster-related deaths have, in most cases, declined in recent decades, heat-related deaths are on the rise.”

In emailed comments, Zaitchik cautioned that the trend should be read carefully, noting that it’s possible that growing awareness is leading more deaths to be reported as heat-related, or an aging population that is more vulnerable to begin with. 

But he was clear about what was driving the trend. “The fact is that we are seeing record-setting heat, year after year.” That growing exposure, “in the absence of adequate adaptation,” is a primary driver of heat-related deaths and illness, he said, adding that multiple studies have found extreme heat “associated with increases in these health impacts, both in Maryland and elsewhere.”

Zaitchik said the storm and related power outages made the deaths in 2012 “a black swan outlier,” but he was “hard-pressed to explain the 2026 numbers in those terms.”

He added that heat-related health impacts are not evenly distributed. “We know that disinvested neighborhoods, often associated with redlining in Baltimore and other cities, tend to experience more extreme heat, and that households in those neighborhoods are less likely to have access to cooling options,” Zaitchik said. 

Those same neighborhoods, he added, tend to have lower life expectancy and higher rates of conditions that heat can worsen, including chronic obstructive pulmonary disease,  cardiovascular disease and asthma. He noted that researchers have not yet confirmed neighborhood-scale differences in how heat and redlining interact with mortality because of limited data. But the evidence on heat and illness “points to the fact that this would be true for mortality risk as well,” he said.

“Summers have gotten hotter, and extreme heat events are becoming more frequent and more intense,” Zaitchik said. “So yes, the baseline risk is absolutely on the rise, and it’s critical that we adapt to this increasing risk.”