Two meta-analyses of mostly time-series designs and case-crossover studies examined the association between heat exposure and mental health problems.

• One found a significant risk ratio (RR) of 1.09 (95% CI 1.06–1.13) for the association between daily suicide rates and an increase in temperature of 7.1°C.
• The other found an overall RR of 1.02 (95% CI 1.01–1.03) for mental health-related mortality for each degree Celsius increase in temperature, and 1.01 (95% CI 1.007–1.015) for mental health-related morbidity.