Background Road traffic fatalities are a major global health burden, with climate factors such as temperature and rainfall potentially influencing crash risks. However, the impact of these factors on road traffic fatalities in specific regions, such as the Greater Kumasi Metropolitan Area (GKMA) in Ghana, remains unstudied.

Objective This study aimed to investigate the influence of temperature and rainfall on road traffic fatalities in the GKMA from 2010 to 2021 using a Bayesian spatiotemporal modeling approach.

Methods Road traffic fatality data from 2010 to 2021 and climate data, including monthly temperature and rainfall were utilized. A Bayesian spatiotemporal Poisson regression model was employed to quantify the associations between climate factors and road traffic fatalities, accounting for spatial and temporal dependencies. The model incorporated both spatial and temporal random effects, and the Besag-York-Mollié (BYM) spatial model was used to separate the spatial effect from other unobserved random effects.

Results A total of 966 road traffic fatalities were recorded in the GKMA from 2010 to 2021, with a median of 1 fatality per month. Spatial and temporal trends revealed relatively constant fatality rates, with higher incidences from April to August and in December. The Bayesian spatiotemporal model indicated that a 1°C decrease in monthly average temperature was associated with a 14.2% increase in fatality incidence (95% CI: -0.198, -0.085), while each additional millimeter of average monthly rainfall was associated with a 1.5% decrease in fatalities (95% CI: -0.035, 0.006). Model-based relative risk predictions showed stable fatality rates in most districts until 2018, with Kwadaso and Suame experiencing significant increases from 2019. Higher relative risks were observed in Suame and Kwadaso during both dry and rainy seasons, while Kumasi had a lower relative risk during both seasons.

Conclusion This study highlights the significant influence of temperatures on road traffic fatalities in the GKMA, with lower temperatures associated with increased fatality risks. The findings inform district specific resource allocation and road safety strategies in the GKMA