Modes of summertime thermal urban stress over major cities in the Middle East: A comprehensive assessment of heat exposure risks

This study examined urban heat dynamics in 21 major Middle Eastern cities from 2003 to 2019. Changes in daytime and nighttime land surface temperature (LST) during summertime were assessed using the least squares regression model. The most pronounced increase in LST was found in Gulf and Arabian Peninsula cities, while higher altitude cities (e.g., Beirut and Sanaa) showed the least warming. The increase in nighttime LST was higher than daytime LST, especially in inland cities. Heat stress exposure was assessed using hot/cold spot categories. Over 11 million people in megacities are at risk of heat stress. Our findings show that most cities had significant day-night thermal risk distribution differences, with heat stress being more common in central urban areas at night and in urban periphery during daytime. City nighttime LST may serve as a more reliable indicator of anthropogenic climate change compared to daytime LST effects, which primarily result from physical factors such as the inflow of hot air from nearby deserts. Also, while built-up areas correlated with hot/cold spots in most cities, a complex relationship exists between vegetation and hot/cold spot patterns. Our study emphasizes well-informed urban planning and adaptable mitigation strategies to protect urban populations from heat stress.