Heatwaves and Early Warning Systems: Perception Data and the Role of Science Communication – A Case Study from Romania

Heatwaves are among the most impactful climate extremes in Europe, driving acute health risks and socio-economic disruption. They are a challenge for early warning and public understanding due to uncertainties in event onset, severity, and human response. Building on the interdisciplinary Strengthening the Research Capacities for Extreme Weather Events in Romania (SCEWERO) project funded by the European Union, this study investigates how scientific evidence, perception data, and communication strategies interact within Romania’s heatwave Early Warning System operated by Meteo-Romania. We analyse both empirical perception data — collected through structured surveys and focus groups to quantify how different communities interpret heat warnings, risk levels, and confidence intervals — and observational heatwave metrics to map divergences between communicated risk and public understanding. This research highlights specific sources of uncertainty faced by forecasters (e.g., variable heat exposure, model forecast spreads), and documents how these uncertainties are interpreted or misinterpreted by non-expert audiences. By tracing how uncertainty in forecast signals propagates through institutional warning messages and into public perception, we identify communication gaps that can lead to maladaptive responses or reduced trust in warnings during heat events. Framing uncertainty, contextualised risk information, and tailored communication strategies improve both public comprehension and behavioural intent during heatwave alerts. We propose evidence-based recommendations for operational Early Warning Systems that move beyond fixed deterministic thresholds, instead incorporating probabilistic messaging where appropriate and grounding risk communication in locally derived perception data. This work illustrates how harmonising scientific uncertainty communication with Early Warning practices can strengthen societal resilience to heatwaves, offering a transferable framework for climate risk communication in other European regions.