Unveiling Riyadh’s Urban Heat Island: A 37-Year Analysis of Temperature Trends and Climate Dynamics

This study presents the first multi-decadal, ground-based characterization of the urban heat island (UHI) in Riyadh, Saudi Arabia, using a 37-year in-situ dataset (1985-2021) from urban (old Riyadh Air Base) and rural (King Khalid International Airport) meteorological stations. The analysis reveals significant warming trends at both sites, with the urban area warming faster (0.07˚C yr−1, p −1, p −1, p −1) and monthly maxima up to 3.03˚C (November 2017). Rapid urbanization—5.5-fold built-up expansion (350 to 1935 km2), impervious cover rising from 45% to 88% in the urban core, and population growth to ~7.5 million—emerged as the dominant driver, amplified by anthropogenic heat, reduced evapotranspiration, and urban canyon effects. Interannual variability was modulated by global (Mount Pinatubo, 1992 cooling), regional (Gulf War aerosols), and local (March-May dust storms) forcings. The Mann-Kendall test confirmed significant UHII intensification in seven months, with spring exhibiting the highest variability (±0.35˚C). A multiple linear regression across 18 arid cities (R2 = 0.81, p < 0.001) validated Riyadh’s UHII as representative, driven by impervious (+0.019˚C per %) and vegetation cover (−0.031˚C per %). These findings directly inform Saudi Vision 2030, supporting Green Riyadh and Saudi Green Initiative targets (10 million trees, 43% green coverage by 2030) through evidence-based strategies: high-albedo materials, drought-tolerant greening, and urban ventilation. By bridging a critical global gap in long-term, ground-validated UHI research in arid megacities, this study sets a new benchmark for sustainable urban resilience under accelerating climate and demographic pressures.