Evaluating Historical Outdoor Thermal Discomfort in the Eastern Mediterranean and the Middle East

Abstract

The Eastern Mediterranean and Middle East (EMME) region is a climate change hotspot experiencing increasing heat extremes. Understanding outdoor thermal discomfort in this region is critical for climate‐resilient urban planning and public health. This study examines the spatial and temporal patterns of thermal discomfort across the EMME over the 1980–2023 period, using ERA5 reanalysis data for dry‐bulb temperature, relative humidity and wind speed. Thermal discomfort is quantified using five indices: effective temperature, heat index, humidex, wet bulb globe temperature and discomfort index. All indices indicate increasing summer thermal discomfort across the region, with a pronounced shift around 1998 that coincides with a ‘mega El Niño’ event and a positive phase of the Indian Ocean Dipole. Cities in the central EMME exhibit the strongest warming, with an annual‐mean increase of 0.54°C per decade—nearly three times the global mean. Warming is strongest in summer, with northern cities warming by up to 0.73°C per decade in summer, compared with 0.52°C per decade for the all‐months (annual‐mean) trend; southeastern cities show a weaker contrast, increasing by up to 0.42°C per decade in summer versus 0.40°C per decade in the annual‐mean. Relative humidity generally declines in northern and central cities, including Tehran and Jerusalem (−1.41% and −1.07% per decade), while southeastern cities such as Riyadh show modest summer increases of 0.37% per decade. Diurnal variability analysis indicates that Abu Dhabi is the only city with a strong linear trend in the summer diurnal temperature range (), whereas the summer diurnal relative humidity range exhibits more pronounced trends, notably in Jerusalem (−0.123% per year, ). Post‐1998, summer warming intensified across the EMME (0.40°C–0.56°C per decade), with northern cities experiencing relative humidity declines of up to 0.66% per decade, highlighting escalating thermal discomfort.

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