The role of temperature and rainfall in traffic congestion: Evidence from 98 Chinese cities

Abstract Improving the performance and resilience of the transportation system in cities is an important way to combat climate change. However, the relationship between weather conditions and traffic congestion remains unclear. This study investigates the association between weather conditions and traffic congestion [congestion delay index (CDI)] using a dataset encompassing 98 cities in China from 2015 to 2019. The results reveal that temperature exerts a significant negative effect on CDI, particularly during weekends. Conversely, rain, wind speed, and relative humidity exhibit significant positive effects on CDI. Specifically, traffic congestion would decrease by 6% when the temperature exceeds 25°C, while it increases by 2%–5.6% with rainfall increases on workdays. Besides, the precipitation–CDI relationship shows an inverse U shape, especially on weekends. Although subways could mitigate the impact of temperature on cities compared to those without subways, the supplementary effect is mild on rainy days. Significance Statement The increasing frequency of extreme weather events poses great threats to cities’ transport systems, and understanding the association between weather conditions and traffic congestion is insightful for future transport planning. The results show that traffic congestion would decrease by 6% when the temperature exceeds 25°C, while it increases by 2%–5.6% with rainfall increases on workdays and the association becomes nonlinear on weekends. Besides, cities equipped with subway systems demonstrate greater resilience to hot weather conditions, although rainfall’s impact remains challenging to mitigate.