When we think of long summer heatwaves, we typically think about daytime highs. But new research from Khalifa University says the nighttime is equally to blame.

Research analyzing data from 491 weather stations from 2005 to 2025 concludes that the frequency of heatwaves is increasing and nights are remaining hotter for longer, particularly along the coasts of the Arabian Gulf and the Red Sea.

CAPTION: Makkah, Saudi Arabia, 15 June 2024: Many Hajj pilgrims are walking on the Arafat field. Mount Arafat (Jabal Arafat, Mountain of Mercy’) is a forgiveness hill. IMAGE: Shutterstock

“Compound heatwaves,” in which both days and nights stay exceedingly hot for days in a row, are dangerous because the human body can’t cool and recover through the night.

The humidity of the coasts factor in largely because humid air traps heat close to the ground. This results in stifling, muggy nights with almost no relief.

The team’s paper, published in Atmospheric Research, was based on the June 2024 lethal heatwave that occurred during the Hajj pilgrimage that exceeded 50 degrees Celsius in certain areas. This resulted in thousands of heat-related illnesses and over 1,300 fatalities.

The four AI weather-forecasting systems tested were able to predict the heatwave but failed to recognize the temperature severity, especially at longer forecast ranges.

While the research concludes that AI forecasting is becoming a useful tool for heat warnings, gaps exist relating to nighttime heat and coastal humidity as Middle Eastern heatwaves increase in intensity.

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