Evaluating the Influence of Traffic Congestion on Surface Urban Heat Island Intensity

Abstract This study quantifies how traffic congestion influences the surface urban heat island intensity (SUHII) in Chicago using GOES LST data and Chicago Transit Authority (CTA) bus speed data. While SUHII is characterized by a well pronounced diurnal cycle that peaks around noon, we observed changes in strength of SUHII that were correlated with changes in traffic speed. This leads to distinct weekend and rush hour effects on SUHII. Citywide, we observed a statistically significant correlation in which each 10 mph decrease in bus speed is associated with an increase of 0.36°C in SUHII. That effect is stronger in highly vegetated, low‐building areas, where traffic‐emitted waste heat is more dominant than other anthropogenic sources. These findings highlight the importance of incorporating congestion metrics into urban heat research, offering new insights for planners and policymakers seeking to mitigate local thermal extremes.