Heat waves are among the most severe extreme climate events, with wide-ranging impacts on human health, agriculture, energy demand, and ecosystems. According to the Intergovernmental Panel on Climate Change, a heat wave is a period of abnormally high temperatures lasting several days or longer, defined relative to local climate thresholds. Their main characteristics are duration (consecutive hot days), intensity (temperature anomalies above normal), and frequency (recurrence of events). Understanding these features is critical for anticipating summer energy demand, assessing agricultural water needs, and evaluating drought risks.

This study investigated the characteristics of heat waves in Egypt using long-term daily maximum and minimum temperatures from ERA5 reanalysis data (1990–2023). Heatwave events were detected for both daytime and nighttime conditions and analyzed in terms of duration, intensity, frequency, seasonal distribution, and temporal trends. The analysis also identified the most common periods of occurrence each year and evaluated whether heatwave activity has intensified in recent decades.

Results show pronounced interannual and seasonal variability in heatwave characteristics across Egypt. Several years—notably 2010, 2015, 2016, and 2021—stand out as exceptionally hot. Heatwaves were most frequent in late July through mid-August, while relatively uncommon during spring and autumn, underscoring their dominance in summer. Although the variability is high, the results suggest a growing tendency toward more frequent and intense heatwave events in recent years. These findings provide critical insights for energy management, agricultural planning, and climate adaptation strategies under a warming climate.