Deadly 119°F Heatwaves are 'Already Here': Why They Are Now Labeled ‘Non-Survivable’ for 2026

"Oh S**t." That was Professor Sarah Perkins-Kirkpatrick's first reaction to the findings of a new study she led into how deadly extreme heat is. The research shows that conditions during six recent heatwaves became non-survivable for people over 65 after just six hours of exposure.

A New Study Reveals Heatwaves Are Already Creating ‘Non-Survivable’ Conditions

A new study that was published in the journal Nature Communications finds that deaths caused by extreme heat have "undoubtedly" gone "seriously underreported." While speaking to The Guardian, one of its co-authors, Professor Ollie Jay, described the dangers bluntly. “Conditions that threaten human life are already here, and the risk moving forward is almost certainly much greater than we previously thought.”

The study relied on a new model that looks at how the human body cools itself through sweating and evaporation. The new method considers age, sun exposure, temperature, and humidity as essential factors. Earlier research mainly considered just air temperature and humidity. The updated approach shows that conditions become "non-survivable" for vulnerable groups at much lower temperatures than previously thought.

After reaching new conclusions about what our bodies can withstand, scientists re-examined six major heatwaves from between 2003 and 2024. One of those heatwaves hit Phoenix, Arizona, in July 2023 and created temperatures that reached 119°F. Researchers found that all of the heatwaves created "non-survivable" conditions for people over 65 who were exposed without shade for just six hours. Some of them created factors that were also deemed deadly for older people, even in the shade.

Like her co-author, the study's lead, Professor Sarah Perkins-Kirkpatrick from the Australian National University, spoke to The Guardian. What she told the outlet vividly depicted how shocked she was by the study's findings. She also explained why she is now worried about the future. "My first thought was ‘oh shit’ – I really didn’t expect to see that, especially when you zoom in to individual cities. If it’s already happening now, then what does a future that is two or three degrees warmer hold?"

Perkins-Kirkpatrick went on to tell the outlet that, based on the study, the dangers from heatwaves need to be considered very differently. “We have often defined heatwaves by temperature alone, and partly that has been because of the data that we had. But using this model of how the body functions, it is a much better way to understand how these events can be deadly.”