With increasing urbanisation and climate change, more people will be exposed to extreme heat. While health impacts of heat are well known, far less is known about how heat and responses to heat affect daily life. Such information is needed if appropriate advice is to be provided on heat adaptation. This study describes heat-related symptoms that can impact wellbeing but do not necessarily require medical treatment, and how heat changes people’s behaviour, including their strategies for relieving heat and seeking heat health advice. Data were collected through an Australia-wide online survey with 1665 responses. We found that heat leads to maladaptive behaviours that could affect long-term health, such as reducing outside activities (67% of respondents) and increasing the consumption of soft drinks (27% of respondents) and alcohol (11% of respondents). Two-thirds of respondents used more air-conditioning to relieve heat stress and many reported poor sleep quality. Behaviour change was strongly correlated with respondents’ age, degree of physical activity and the extent to which people sought advice on heat and health (37% of respondents). The results can help identify individuals least likely to cope well with heat and who may benefit most from heat relief advice.