Variation in the Extreme Temperatures and Related Climate Indices for the Marche Region, Italy

This paper presents a study on the evolution of extreme temperatures in the Marche region, Central Italy. To this end, a complete dataset compiled using data collected from available thermometric stations over the years 1957–2019 based on minimum and maximum daily temperatures was selected. The yearly mean values of extreme temperature and relative climate indices defined by the Expert Team on Climate Change Detection and Indices were calculated, and a trend analysis was performed. The spatial distribution of the trends was assessed, and the variations in extreme temperatures in the medium–long term were considered by calculating mean values with respect to different climatological standard normals and decades. The analyzed parameters show that extreme heat events characterized by increasing intensity and frequency have occurred over the years, while cold weather events have decreased. A high percentage of stations recorded an increase in all indices related to daily maximum temperatures, and a simultaneous decline of those related to daily minimum values, under both nighttime and daytime conditions. This phenomenon characterizes the entire Marche region. A detailed analysis of the heat wave indices confirms an increasing trend, with a notable increase beginning in the early 1980s.