Using a comparison between a 1960s and a 2020-2024 average, the analysis issues a stark warning about the speed and scale at which extremely hot days – measured as more than 35 degrees Celsius / 95 degrees Fahrenheit – are increasing for almost half a billion children worldwide, many without the infrastructure or services to endure it. This project aims to produce heatwave indicators globally and measure the exposure of child population on extreme heatwaves indicator values and significant changes in them over time.