Summer heatwave travel behaviour adaptations vary across purposes, modes, space, and time

During summer heatwaves, travel modes and trip timings provide insights into heat exposure and adaptive responses; however, the moderating roles of trip purposes, space, and time remain underexplored. This analysis links England’s National Travel Survey with ERA5 climate reanalysis data, defining heatwaves using a heat index (‘feels like’ temperature). Probit discrete choice models of travel modes and Cox proportional hazards models of departure times assess differences across trip purposes and spatio-temporal factors. The models estimate population-level associations for trips longer than one mile and provide limited evidence of uniform differences during heatwaves; both travel behaviours vary widely across space and time. The relationships suggest that typically cooler locations exhibit travel behaviours consistent with heat-avoidance during extreme heatwaves, urbanization is associated with greater public transit usage and heat-avoidant departure timing, and over 15 years, there are tendencies towards typically more sheltered modes for commuting and heat-avoidant departure timing during extreme heatwaves.