Considerations regarding the naming of heatwaves

At the second session of the Commission for Weather, Climate, Water and Related Environmental Services and Applications (SERCOM-2) (Oct 2022), WMO Members considered the practice of naming heatwaves, and expressed caution in adopting or promoting this practice. Members requested WMO to focus attention on strengthening heat-health warning systems, enhancing technical heat forecasting capabilities, and building capacity and partnerships to protect vulnerable communities from extreme heat.

Major recommendations are as follows:

• Decoupling naming and early warning, as well as inappropriate naming, could bring unintended negative consequences and reduce the effectiveness of established heat advisory and response measures, since there is no standard classification or ranking system for extreme temperature events, including heatwaves.
• The additional act of “naming heatwaves” does not assist with the identification or characterization of extreme temperature events. 
• Heatwaves can be forecast up to 10 days in advance in many areas (mainly extra-tropics and high latitudes) but lack skill at 3-day lead-times in many regions (mainly tropics). Forecast-based naming creates additional challenges that named events might not transpire, turn out to be less severe, or occur in different localities, potentially undermining any benefits of raised awareness through naming, and creating false alarms.
• NMHS should consider the impact on duties and services of communication and emergency operations staff. The time burden for NMHS, health authorities and other civil protection authorities to engage with a naming scheme, including its coordination and providing technical clarifications to other civil authorities, and the media will detract staff focus from providing official EWS/advisory services and life saving interventions. 
• To prevent confusion and interference with authoritative operational procedures and protocols, coordination of pilot heatwave naming with the official heat advisory systems in a country is recommended.