Giant 'heat storms' are scorching Earth

We are in the age of heat storms.

In less than a lifetime, about six and a half decades, heat waves have evolved from sporadic, isolated episodes to massive, cascading weather events that can blanket vast swaths of the planet for months or even years at a time.

The largest heat wave of the 1960s reached about 6% of the planet as it drifted for 46 days over the Atlantic Ocean, parts of Latin America and West Africa.

The largest one this decade swept across almost 85% of the globe during its 367-day lifetime in 2023 and 2024, stretching into the polar latitudes and touching virtually every human being on Earth.

To continue calling such sprawling phenomena “heat waves” would be like calling a monsoon a rain shower. To understand the new reality of these immense expanses of heat, we analyzed temperatures for every hour of every day since 1960 for more than one million grid squares covering the entire globe. Out of those results, we developed a new concept: the “heat storm.”

Our data-driven examination of global temperatures reveals the emergence of these heat storms and how they are upending life around the world from Texas to Ivory Coast to Poland.

We want to show how far the effects of heat storms have reached around the world. How have extreme weather events shaped your year? Share your experience with our journalists in this form.

This was the most complex analysis I have ever attempted. It didn’t seem that way when News Applications Editor Ben Welsh and I started noodling with this idea back in 2024. But the planet is a complex system, full of surprises and wonders. This journey was no different.

Every decision, from how to define a heat wave for each of the more than one million spots on the planet to how to merge them into a cohesive weather phenomenon that people could see on a map, had cascading effects through the analysis that hurt my brain, tested the patience of my editors and cost us months of time. – Maurice

Maurice Tamman has worked for the Reuters enterprise team since 2011 and before that was at the Wall Street Journal. He has written award-winning investigative pieces on subjects ranging from how fisheries are shifting in response to climate change, to Medicare fraud and abuse. Most recently, he was the lead on Reuters' "Fentanyl Express" series, which won the 2025 Pulitzer Prize for Investigative Reporting. He is also an avid sailor.