Deadly Heat: The Association Between Ambient Temperature and Suicide in Young People in the United States

OBJECTIVE: The impact of higher ambient temperature on suicide is well documented in the general population, although it remains unclear in youths despite their particular biosocial vulnerability. In an ecological study, the authors examined this relationship, focusing on seasonal differences. METHODS: The authors calculated monthly suicide rates in young people (ages 5-24) by county using data from the U.S. Centers for Disease Control and Prevention and the U.S. Census Bureau from 1980 to 2004 in the contiguous United States. Fixed-effects regression was used to estimate relative risk of suicide per 1°C change in average monthly temperature overall and by season, accounting for precipitation, region, county, month, and year. Age-stratified analysis (ages 4 to 65+) assessed whether effects were unique to young people. Heterogeneity models examined the impacts of legal sex, income, race, education, geographic division, and rurality. RESULTS: Averaged across seasons, suicide in young people increased 0.75% (95% CI=0.34, 1.16) per 1°C increase, comparable to the general population (0.73%, 95% CI=0.53, 0.93). This effect was significant only in summer, and it was substantially larger in summer (2.68% per 1°C; 95% CI=1.42, 3.94). Age stratification showed that 15- to 24-year-olds were uniquely vulnerable compared to other age groups (2.97% per 1°C; 95% CI=1.30, 4.65). Most geographic regions experienced this association, and no sociodemographic differences were identified. CONCLUSIONS: Summer heat is associated with higher suicide rates among late adolescents and young adults, who appear most at risk. This association likely reflects neurobiological and socioenvironmental conditions of young people that amplify heat-related mental health risk. These data highlight the need to study how ambient temperature impacts youth mental health and develop biosocially informed interventions as temperatures rise.