Post-Sunset Humid-Heat Maxima near the Southern Persian/Arabian Gulf

Abstract

Abstract Previous studies have firmly established that extreme humid heat is a prominent climate hazard in coastal portions of the Arabian Peninsula. However, many of its associated features, such as diurnal and spatial variations, remain incompletely explored. Here we present evidence from four independent datasets that evening or nighttime daily maxima in extreme wet-bulb temperature and heat index are widespread along the southern Persian/Arabian Gulf coastline and adjacent inland desert, driven principally by sea-breeze-related movements of moist maritime air. This timing runs counter to the general expectation of greater heat-stress risk during daytime hours. While wet-bulb temperature is not the only metric relevant for understanding heat hazards, its values in coastal Arabia are already closer to the uncompensable-heat limit than anywhere else in the world. Deviations from a simple diurnal assumption about heat risks are thus of critical importance and heighten the value of improved understanding of extreme-humid-heat meteorology, in this region and in ones subject to similar physical processes.