Associations between meteorological factors and hemorrhagic stroke mortality risk in Hefei, China: a time-series study from a subtropical city

Hemorrhagic stroke (HS) remains a major cause of mortality, but evidence regarding the short-term effects of meteorological factors on HS deaths is limited. This study evaluated the associations of daily mean temperature (Tmean), relative humidity (RH), and diurnal temperature range (DTR) with HS mortality in Hefei, China, from 2017 to 2022. We analyzed 19,682 HS deaths using a generalized additive model combined with a distributed lag nonlinear model and generalized additive models, adjusting for air pollutants, long-term and seasonal trends, day of the week, and public holidays. The results showed that low Tmean was strongly associated with increased HS mortality. Low RH was associated with a modest increase in mortality risk, whereas DTR showed little evidence of an association. Age-stratified analyses suggested earlier and more sustained effects of low Tmean among older adults. Sensitivity and time-stratified case-crossover analyses confirmed the robustness of the findings. These findings support targeted weather-related public health interventions and preventive strategies.