Meet the heat storm: 7 takeaways from our investigation that gave supersized heat waves a new name

Reuters analyzed global temperatures hourly from 1960 onward and consulted two dozen climate researchers to define a ‘heat storm’: a heat wave at its peak covering at least 1% of Earth. The investigation estimates about five active heat storms per year in the 1960s versus an average of 102 per year in this decade; one 2023–24 event lasted 367 days and touched nearly 85% of the globe. It connects these events to heat’s effects on health, work, ecosystems and livelihoods and supplies a live tracker.

The report publishes its temperature dataset and methodology and interviews climate scientists about impacts across several regions. It translates climate scale into practical questions about cooling, schools, work and local preparation. ‘Heat storm’ is Reuters’ own analytical category, not a universal scientific term; thresholds and comparisons should be judged against the published methodology, and the report does not attribute each local impact solely to climate change.