Forecasting European heat-related mortality in 2024: data-driven vs physics-based forecast approaches

Heat has emerged as a major public health concern. Over 62,000 heat-related deaths were estimated to have occurred during the European summer of 2024, exemplifying the pressing need to develop effective early warning systems. Such systems depend critically on the quality of the underlying forecasts, and recent work has focused on developing impact-based forecasts for heat-related mortality, which provide explicitly impact-oriented information. To date, heat-related mortality forecasts have been based on the output of numerical weather prediction models, or physics-based forecasts. The field of weather forecasting is undergoing a rapid transformation with the advent of skillful data-driven forecasts. This case study compares European heat-related mortality forecasts for 2024 based on physics-based weather forecasts with those based on data-driven weather forecasts. Our results highlight the non-linear relationship between temperature and mortality, and the sensitivity of forecasts to errors at high temperatures, although the generalisability of our results is hampered by the small sample size. The targeted improvement of forecast models for high temperatures would be particularly beneficial for heat-related mortality forecasting, and we suggest the application of this approach to both data-driven and physics-based forecast ensembles as an important next step in the continued development of informative, explicitly impact oriented forecasts.