Successive Hours of Heat Stress in Athens Based on the Universal Thermal Climate Index (1960–2024)

The study explores long-term changes in the maximum number of consecutive hours per day of heat-related discomfort in Athens over the period 1960–2024, using the Universal Thermal Climate Index (UTCI). This index includes a four-category scale to represent heat stress intensity, ranging from ‘moderate’ to ‘extreme’, as part of its broader multi-category classification system. The analysis indicated a clear increase in the frequency of days with a large number of consecutive discomfort hours over the past decades. Almost 70% of the total number of days with 11 consecutive hours under at least ‘strong heat stress’ and 7 consecutive hours under at least ‘very strong heat stress’ were detected after the year 2000.