Recent tendencies of extreme heat events in Italy

Over the last 20 years, several record-breaking events linked to high air temperatures have enhanced the attention over extreme heat phenomena, especially during summer. Both 2022 and 2023 have been exceptional years in this regard. Heat waves, in particular, are a major natural hazard for the most fragile groups of the population. In order to address the points of impact, adaptation and future predictions, a quantitative analysis of all their specific aspects is necessary. These include the monitoring of their changes over time. This study consists of a comprehensive analysis at national level of several air temperature-extremes indices over Italy, including those specifically related to heat waves. The dataset is based upon a set of high quality daily maximum and minimum air temperature records, from more than 250 ground-based weather stations. The time frame considered ranges from 1991 to 2020, providing information about the present Italian climate. Two analyses are reported. One is targeted to find local features and is based on single stations data. The second one looks for a global signal related to heat extremes. The double level of the information (local and global) can be very useful in the comparison of results. The two methods are in agreement in describing an increasing presence of heat extremes, in terms of overall frequency, duration and intensity. Some areas appear as hot spots for the observed tendencies.