Introduction The relationship between temperature and mortality has been well documented in the literature, with studies examining the effects of both temperature variations and extremes. The impact of temperature on morbidity however has received far less attention. In particular, to date there has been no study of the existing literature examining the effect temperature has on morbidity.

Methods This study incorporates a review and meta-analysis of the literature on the relationship between temperature and morbidity. Utilising a number of different electronic databases, a comprehensive search was performed, the results of which were filtered against pre-defined selection criteria. Subgroups were defined according to type of morbidity and whether a heat or cold effect was examined. The studies were combined using both fixed and random effects models to examine both heterogeneity and the effect of a unit change in temperature.

Results 37 studies were selected to be included in the review. Studies only listing correlations were analysed separately from those reporting actual responses in morbidity per unit change in temperature. In particular, for hot effects an increase in 1^°C resulted in an increased risk of morbidity (RR: 1.002, 95% CI 1.001 to 1.003), and similarly for a 1°C decrease in temperature for cold effects (RR: 1.003, 95% CI 1.002 to 1.005).

Conclusion This study provides a thorough survey of the literature relating to the effects of temperature on morbidity. The mean effects of temperature were found from relevant studies, along with an examination of important subgroups.