Heat Waves in Portugal During the 2001–2024 Period: An Overview

The present contribution addresses the Heat Waves (HWs) which occurred in Portugal’s mainland during the first 24 years of the XXI century: the number of HWs, their frequency, duration and geographic localization, among other impacts, are described. In a complementary perspective, due to the significant impacts of the 2003 HW, specifically in terms of mortality, a more detailed analysis of this event is performed. For the present analysis, HWs were identified using a modified version of the Heat Wave Duration Index (HWDI) proposed by the World Meteorological Organization (WMO). During the XXI century, between 2001 and 2024, 95 HWs occurred in the Portuguese mainland. In 2024, eight HWs occurred, followed by 2009, 2015 and 2017, with seven HWs each; in terms of monthly distribution, August (17) and May (16) displayed the highest values. HWs are now included in the World Health Organization agenda of natural hazards, enhancing the importance of these events. It is time to start considering HWs and their significant impacts as an important issue, especially in countries with older populations, like Portugal.