By SCCF Policy Associate Allie Pecenka

As Southwest Florida residents and visitors know, hot days are par for the course during summer. Some days, though, push the threshold of expected summer temperatures and can be classified as “extreme heat days.” 

While there are several ways to define extreme heat, a qualifying event is often based on temperature and humidity deviations from historic, seasonal averages in a given area. As global climate change contributes to higher average temperatures, the likelihood of extreme heat days and prolonged heat waves increases.

A 2025 study conducted by the World Weather Attribution, Climate Central, and the Red Cross Red Crescent Climate Center highlights the role of anthropogenic (human-caused) climate change on producing more global heatwaves and the scope of people impacted by these events over a 12-month period (May 1, 2024- May 1, 2025). The report explains that this 12-month period of analysis spanned Earth’s hottest year on record, surpassing 2023, which previously earned that title. Key findings from this study include the following:

• From May 1, 2024 to May 1, 2025, 4 billion people — about 49% of the global population — experienced at least 30 days of extreme heat (hotter than 90% of temperatures observed in their local area from 1991-2020).
• In 195 countries and territories, climate change at least doubled the number of extreme heat days, as compared to a world without climate change.
• All 67 extreme heat events — identified as significant based on record-setting temperatures or major impacts to people or property — were found to be influenced by climate change. 

The report mentions the critical importance of strong systems for tracking and reporting on extreme heat impacts as they become more commonplace. 

Heat waves and the associated health complications from these events comprise the single highest cause of weather-related deaths in the U.S., leading to an estimated 1,300 fatalities each year. Children, older individuals, and those with chronic diseases are at the highest risk for heat related complications, though no population is immune to these impacts. 

Extreme heat also affects plants and wildlife, on both immediate and longterm scales. Individual extreme heat events may harm wildlife causing dehydration and energy loss, disrupting foraging behavior, and increasing predation risk, among many other impacts. On a larger scale, global climate change threatens biodiversity by shifting ranges for species, increasing habitat loss and disease outbreaks, and creating food chain disruptions.

To help wildlife in extreme heat, you can provide small water sources in your yard and create spaces with shade. Planting native plants is one of the most effective ways to create shade — native trees, shrubs, and ground covers naturally provide refuge to many insects, birds, and other animals.

Increased global temperatures also introduce higher chances of extreme weather such as stronger rainfall events, stronger hurricanes, or prolonged droughts. A 2024 study published in Environmental Research: Climate displayed the link between ocean warming as a result of climate change and the intensification of recent hurricanes. One key finding was that “30 of 38 hurricanes studied reached intensities roughly 1 category higher on the Saffir-Simpson Hurricane Wind Scale than their expected strength in a world without climate change.” 

At a local scale, this summer has a 50% chance of being hotter than average in much of Florida, based on data from the National Weather Service’s Climate Prediction Center. 

Understanding the far-reaching impacts of extreme heat and warming ocean temperatures as a result of climate change can serve as the first step towards combating their impacts. Informed individuals can act to protect themselves, their communities, and wildlife from complications of extreme heat.

One of the most powerful actions you can take is to advocate for policies that support strong scientific monitoring of climate impacts, as well as those leading to decreased carbon emissions on local, national, and global scales.