Temperature anomalies, rainfall duration and road accidents: a nationwide analysis in Portugal

Status: Under review at Transportation Research Part D.

Abstract

Climate change is expected to intensify extreme heat and rainfall, yet its implications for road safety remain insufficiently understood. Existing research has focused on absolute weather levels using official accident statistics, which are delayed and omit less severe incidents. We examine weather anomalies and traffic accidents in mainland Portugal using a daily municipality-level panel (2021–2025) combining crowdsourced accident reports with hourly reanalysis. Exposure is defined relative to municipality-specific climatological baselines and estimated by Poisson pseudo-maximum likelihood. A one standard deviation increase in the daily temperature anomaly is associated with 4.5\% more expected accidents, and the same increase in wet-hour exposure with 9.4\%, significantly larger than that for daily total rainfall. Conditional on the daily mean anomaly, additional hours in the local cold tail are associated with higher counts, although cold days overall are associated with fewer accidents. The response to wet-hour exposure declines from freeways to local streets.

Keywords

• Temperature anomalies
• Road traffic accidents
• Rainfall duration
• Climate exposure
• Crowdsourced data

Suggested Citation

Pandit, Dhruv Akshay and de Castro Neto, Miguel and Marques Rodrigues, Paulo Manuel, Temperature anomalies, rainfall duration and road accidents: a nationwide analysis in Portugal. Available at SSRN: https://ssrn.com/abstract=7550196 or http://dx.doi.org/10.2139/ssrn.7550196