Lived experiences and predictors of mental wellbeing impacts during the 2022 UK summer heatwave.

While research into heatwaves and mental health is expanding rapidly, the sub-clinical wellbeing impacts of extreme heat remain understudied. This study examined how UK residents' mental wellbeing was affected during the unprecedented July 2022 heatwave and identified key predictors of vulnerability to heat-related psychological impacts. Using mixed-methods analysis of national survey data (N = 1485), we found that nearly half (43.5 %) of participants experienced negative wellbeing effects during the heatwave. These impacts ranged from negative emotions and moods, to adverse cognitive, physical, and social effects. Hierarchical ordinal regression revealed that age, distance from greenspace, caring responsibilities, and disability/long-term health conditions significantly predicted greater vulnerability, while community belonging and psychological resilience emerged as protective factors. With extreme heat events projected to increase across the UK due to climate change, these findings highlight an urgent need for public health and adaptation policies to address the substantial sub-clinical mental wellbeing impacts of heatwaves and the intersecting vulnerabilities that amplify risk.