Comparing the period from 1991 to 2020 with that from 1971 to 2000, the average number of summer days increased from 39 to 49 per year and the number of hot days from 8 to 13. The number of tropical nights, when the temperature does not fall below 20 degrees, rose from 1.1 to 1.3. According to the data cited in the Klimarisikoanalyse (Climate Risk Analysis), the number of ice days has decreased from 20 to 17 per year. According to the data, heat stress has a particularly strong impact on vulnerable population groups such as the elderly, those with pre-existing conditions, and young children.