Do the public take action when a severe snow warning is issued?

Extreme weather events pose significant risks, making timely warnings essential for preparedness. The Met Office’s National Severe Weather Warning Service (NSWWS) has issued impact-based alerts for over a decade, yet evaluations of their effectiveness remain limited. This study uses anonymised mobile phone data to analyse over 100 million road trips during snow warnings on 31 January 2019. Southwest England and south Wales saw fewer long trips (-14%) and more short trips (+5%), with work travel down 20% nationwide. These findings indicate that warnings influence behaviour before hazards occur, but responses beyond warning areas highlight a need for clearer communication.