Highlights • Cooling behaviours an area of increasing interest under rising heat in cities. • Survey of public in Fukuoka, Japan, assesses cooling behaviour and climate awareness. • Some people use air conditioning with mitigation focus, others emphasise adaptation. • Those emphasising mitigation have lower bills and more likely to engage in other behaviours. • Messaging on air conditioning use and promoting urban greening may enable co-benefits., Under a warming climate and urban heat island effects, cooling behaviours are increasingly important for city dwellers. Cooling actions, especially air conditioning, receive increasing scrutiny in social science, as does engagement and communication on behaviours spanning adaptation and mitigation. In response, this paper evaluates the relation between residents’ adaptation and mitigation behaviours around cooling in Fukuoka, Japan, and draws lessons for communication on encouraging adaptation and mitigation actions. A survey distributed to residents in six areas of Fukuoka, Japan, assessed perceptions of global warming and urban heat island effects, frequency of mitigation and adaptation behaviours, use of air conditioning, electricity bills and evaluation of green spaces. We observe a difference between respondents using air conditioning with an energy-saving (i.e. mitigation) focus, versus those using air conditioning with an adaptation (i.e. cooling) focus. We also note residents emphasising mitigation behaviours may use shade in parks or cooling centres as alternative cooling strategies, but that awareness of effective air conditioning use may be lacking. Our findings build on existing literature by reinforcing – in a subtropical context – the need to reconsider practices around air conditioner use; and illustrate the value of a breadth of messages to promote joint mitigation and adaptation actions.