Yearlong Heat Storm Covered Nearly 85% of Earth

Reuters’ analysis introduces “heat storms” for the largest heat waves, defined as periods of at least five consecutive days of unusually high temperatures that cover at least 1% of the globe at their peak. Using global hourly temperature data since 1960 and input from climate researchers, the investigation finds that heat storms increased from about five active events a year in the 1960s to roughly 102 a year in the current decade. The largest recorded event, Heat Storm Vera, lasted 367 days across 2023 and 2024 and covered nearly 85% of the planet. Reuters also describes heat-storm cascades—successive or overlapping events—with one cascade continuing since 2008, while connecting the growing scale and frequency of extreme heat to rising greenhouse-gas emissions. The reporting frames heat waves as a way to make the effects of climate change more tangible in everyday life, citing impacts ranging from deadly heat in Europe to harm to people, wildlife and livelihoods elsewhere.