In brief
- Post-storm power outages and heat waves are a dangerous combination.
- Climate change is increasing the chance of extremely hot weather coinciding with a hurricane.
- Experts believe heat kills far more people than is officially documented.
- Efforts to improve electrical infrastructure and protect vulnerable people, like older adults, can save lives.
On July 8, 2024, Hurricane Beryl made landfall near Matagorda, Texas, as a Category 1 hurricane with 80 mph (130 km/h) winds. The storm’s eyewall passed over heavily populated Houston, triggering a massive and deadly power outage that affected 2.7 million customers. Over 1 million customers in Houston were without electricity three days later, and 226,000 were still without power eight days later. The day after Beryl hit, Houston Hobby Airport hit 97 degrees Fahrenheit (36.1°C), with a heat index of 104 degrees Fahrenheit (40°C), prompting a heat advisory by the National Weather Service, warning that those with no air conditioning could suffer from heat-related illnesses and that “the widespread loss of power and air conditioning across [southeast Texas] could make for dangerous conditions.”
The heat wave continued for over a week, with Houston recording a heat index of 110 degrees Fahrenheit (43.3°C) on July 16, 2024 — eight days after Beryl’s landfall. According to the National Hurricane Center, 14 heat-related deaths occurred in Texas in the aftermath of Beryl, and 553 heat‐related illness encounters were reported by Harris County Public Health over the period July 9-15, 2024. This deadly event was analyzed in a recent thought-provoking study led by Andrew Grundstein of the University of Georgia, “The Fifth Hurricane Hazard: A Case Study of Heat Risks Faced by Disaster Relief Workers After Hurricane Beryl’s Landfall.”
The fifth major hurricane hazard: post-storm heat waves
Historically, hurricanes have caused four main hazards: wind, storm surge, heavy rain, and tornadoes. But we can now add an increasingly dangerous fifth hazard: hotter post-landfall heat waves after a massive storm-caused power failure. In the old climate, hurricanes typically struck after the peak summer season for heat waves. But as the climate warms and heat waves occur later in the year, the chance of extremely hot weather coinciding with a hurricane increases. And since 1970, the Atlantic hurricane season has been getting longer, with the increases mainly associated with storms forming earlier in the calendar year, when extreme heat is also more likely. Hurricane Beryl of 2024 in Houston was a harbinger in that regard, hitting the city on July 8 — over two months before the peak of hurricane season.
With global warming making people increasingly dependent on air conditioning, power failures from hurricanes, followed by heat waves, are creating increasingly hazardous risks to health. A century ago, many people in hurricane country – even those of modest means – lived in structures designed to cool down naturally. For example, the notorious “shotgun shacks,” narrow single-story homes, were smartly designed for hot climates, with long side hallways that allowed breezes to blow from front to back. Modern structures designed with air conditioning in mind (including large picture windows that don’t necessarily open, for example) could be much more prone to heating up when the power is out.
Research shows that heat waves occurring in conjunction with extreme winds and heavy rainfall significantly amplify the extent and duration of outages, often resulting in cascading failures and prolonged recovery times. In a 2025 interview, climate scientist Michael Oppenheimer of Princeton said, “These are not just individual risks, they are combined risks. Consequences can be more severe than the sum of damages expected from the individual events because they interact with each other, the damages from the first worsening the effect of the second event.”
The fatality risk in a heat wave can triple without air conditioning, as revealed by a post-heat wave analysis of the deadly 1995 Chicago heat wave. Since 2017, there have been four U.S. hurricane landfalls where multiple heat-related deaths occurred during a heat wave that followed massive post-storm power outages: Hurricane Beryl of 2024 (14 deaths in Houston), Hurricane Irma of 2017 (14 deaths in South Florida), Hurricane Laura of 2020 (nine deaths in southwest Louisiana), and Hurricane Ida of 2021 (11 deaths in the New Orleans, Louisiana region).
Hurricanes can intensify heat waves
For slow-moving hurricanes, the risk of a significant heat wave after landfall is often reduced because of lingering cloud cover, which lowers temperatures. Fast-moving mainland U.S. landfalling hurricanes are often caught in an upper-level trough of low pressure, and the associated cold front at the surface will often push through the damaged area, bringing cooler, drier air and reducing heat wave odds. But for many hurricanes hitting during the hottest time of year, the dry, sinking air that occurs on the periphery of the storm can bring hot and sunny weather and heat wave conditions in their aftermath, with high-humidity air from the storm’s heavy rains contributing to the danger. This is particularly true in the Caribbean. A 2022 study of 53 named storms from 1991-2020, Hurricanes and Anomalous Heat in the Caribbean, found that after these storms passed main cities in 14 Caribbean islands, the heat index increased in every case studied, by as much as nine degrees Fahrenheit (5°C).
Furthermore, defoliation of vegetation by a hurricane can increase temperatures and reduce shade, raising heat stress. A 2023 paper, Elevated heat indices resulting from hurricane-related defoliation: a case study, estimated that defoliation by Hurricane Laura in 2020 could have increased people’s exposure time to high heat indices by 8%, with an increase in the heat index of up to 2.2 degrees Fahrenheit (1.2°C).
Heat’s actual toll: 10 times higher?
In a post on the Climate Brink in the aftermath of Hurricane Beryl’s 2024 strike on Houston, How many people did the Beryl blackout kill?, climate scientist Andrew Dessler wrote: “Measuring heat-related deaths is challenging. When someone dies during a heat wave, the cause might be recorded as a heart attack, stroke, or respiratory failure, without acknowledging that heat played a role in triggering these conditions. This leads to chronic underestimations of the true toll of heat on public health.”
He estimated that the post-Hurricane Beryl heat wave was responsible for on the order of 100 deaths — far greater than the 14 official heat-related deaths. And according to a 2024 interview with University of Washington epidemiologist Kristie Ebi, “The CDC’s estimate of heat deaths, about 1,200 Americans a year, is probably at least a tenfold undercount.”
A 2020 study of Florida nursing home residents in the aftermath of Hurricane Irma found that power loss was associated with a 25% increase in mortality at seven days after landfall, and a 10% increase after 30 days.
In a stunning paper released in 2024, “Mortality caused by tropical cyclones in the United States,” Rachel Young and Solomon Tsiang found that the average U.S. hurricane landfalling between 1930 and 2015 caused 24 direct deaths. However, they observed an increase in excess deaths – mortality beyond what would otherwise be expected in that period – that lingered for 15 years, totaling 7,000-11,000 excess deaths per storm. Although the paper did not examine the potential causes of these extraordinarily increased death rates, it is certainly possible that post-storm power outages during heat waves contributed. The largest single category of deaths was from cardiovascular disease (36%), which increases with excess heat.
The concerning future of compound hurricane and heat wave events
The odds of compound tropical cyclone-heat events are likely to exponentially increase over the next 30 years because of the sharp increase in humid heat expected in the tropics, according to a 2019 paper, An emerging tropical cyclone–deadly heat compound hazard. The authors’ definition of a compound tropical cyclone-heat event had about a one-in-10-year recurrence frequency globally under the historical 1980-2010 climate, but would increase by nearly a factor of four (11 events in 30 years) for 2 degrees Celsius of global warming. This is likely a considerable underestimate, though, since just changes in heat were considered — not changes in hurricanes. Since future hurricanes are likely to be stronger, wetter, and perhaps slower-moving, this will increase their potential to cause power outages.
The paper concluded with this prescient warning: “Our results present a simple but stark warning: with no change in tropical cyclones but plausible rises in the heat index, potentially deadly heat waves are more likely to follow tropical cyclones and eventually strike vulnerable populations. Although a tropical cyclone-heat event has not yet impacted a heavily populated coastline, the likelihood is growing.” That was 2019. Since then, hurricane and heat wave events have affected millions of people in places like Florida and New Orleans.
In a 2022 paper, researchers from Princeton University and the Huazhong University of Science and Technology in China studied Houston’s future hurricane-heat wave risk. The study found that the odds of residents experiencing a greater than five-day post-hurricane heat wave without power in a 20-year period would increase by over a factor of six from the historical climate (1980–1999) to the middle-century (2040–2059) time frame. These odds would increase if considering that outdoor workers repairing the grid can work for only limited hours (<75% of normal hours) under extreme heat and humidity — a heat index greater than 103 degrees Fahrenheit (39.4°C) — according to the Occupational Safety and Health Administration (OSHA) rules.
At the same time that heat wave likelihood is increasing, so is the risk of power outages. A 2025 paper, Projected increases in tropical cyclone-induced U.S. electric power outage risk, used the latest generation of Intergovernmental Panel on Climate Change models to study the risk of power outages from landfalling hurricanes. The research found that this risk will significantly increase everywhere because of the higher winds, heavier rains, and slower movement of hurricanes at landfall. Inclusion of rainfall accounted for over 20% of the future outage risk increase in the U.S., with the proportion rising above 30% in the Carolinas and inland U.S., and above 50% in parts of the Northeast.
A 2024 study by the Electric Power Research Institute and the Pacific Northwest National Laboratory found that by the end of the century, under a high-emissions scenario, the most hurricane-prone regions of the U.S. coast will experience 0.5-2 additional severe power outages per decade as a result of global warming–induced changes in hurricane activity.
Solutions for adaptation
Measures to adapt to the increasing threat of hurricane and heat wave compound events are clearly needed and are relatively straightforward. Investing in power grid resiliency is a must — for example, adding more backup generators and microgrids that utilize solar power. One promising technology: stand-alone balcony solar panels or a $700 portable air conditioner powered by a solar panel that could cool a single room. And strategically burying just 5% of power lines — specifically those near main distribution points — would almost halve the number of affected residents, one study of Houston’s vulnerability found.
Read: The solar panels Germans are plugging into their walls
The U.S. electrical grid is in poor shape, according to the American Society of Civil Engineers. In its 2025 Infrastructure Report Card, the society downgraded its rating for the energy sector (which includes electrical transmission) from a C- (given in 2021) to a D+, because of concerns related to capacity, future needs, and safety. The report said that the grid required hundreds of billions in additional investment. The authors commented that better codes and standards that could help build more resilient electricity transmission and distribution networks are available, but these are often not required, “leading to system failures in the face of extreme weather events.” For example: “To restore power as quickly as possible, building codes currently do not require providers to replace fallen poles with stronger poles that are less likely to fail. Instead, historically, a pole is allowed to be replaced under the same specifications that were used for installing the destroyed or damaged pole.”
Efforts to protect older adults – the most vulnerable to heat – are of paramount importance. After Hurricane Irma in 2017, Florida enacted legislation requiring nursing homes to have emergency power sources and additional fuel capable of providing air conditioning for at least 96 hours. This was not cheap: The Florida legislature estimated that the five-year costs to come into compliance were over $120 million. And since 2016, the U.S. Centers for Medicare & Medicaid Services has similarly required medical institutions participating in Medicare to follow emergency preparedness requirements, including alternative power sources and safe evacuation plans.
Related posts
Bob Henson contributed to this post.
Republish our articles for free, online or in print, under a Creative Commons license.
