Heatwaves are becoming more frequent, more intense, and more dangerous—especially for older people. In many parts of Austria, the number of hot days has reached record levels in 2024. With demographic change accelerating, the health risks associated with extreme heat are expected to grow significantly in the coming years.
To help understand these developments, the Complexity Science Hub has updated its interactive heat map with the latest data for 2024.
The map shows two key indicators:
The heat index, which displays the number of days with temperatures exceeding 30°C at the district and municipality level (2018–2024), and
The heat stress index, which combines the number of hot days with the proportion of people aged 65 and older—highlighting regions where health risks are particularly high.
KEY FINDINGS FROM THE 2024 DATA
Record-breaking heat days: 49 districts experienced at least 34 hot days (above 30°C)—compared to only 15 in the previous peak year, 2019.
Rising trend across the country: While a few municipalities saw a slight decrease, the overall trend is clearly upward.
Severely affected – Burgenland and Lower Austria: All districts in Burgenland and nearly all in Lower Austria recorded very high heat index values (more than 34 hot days).
Severely affected – Carinthia: In 7 out of 10 districts, the heat stress index was rated “very high” in 2024—due to both a high number of hot days and a larger share of older residents.
Striking East-West differences: The eastern part of Austria experienced significantly more hot days and tropical nights than the west. To give one example – the city of Bregenz recorded 12 hot days, while Rust had 52. Additionally, the share of people over 65 in Rust is 27.7%, compared to 19% in Bregenz.
Vienna: With an average of 49.4 hot days and up to 53 tropical nights in districts such as Wieden, Margareten, and Mariahilf, the city faced extreme heat—though it has a comparatively young population (only 16.4% over 65).
Tropical nights (over 20°C): While most municipalities in Tyrol and Salzburg recorded almost none, districts in Burgenland averaged nearly 20, and Vienna over 40 (43.21 on average, or 40.5 when accounting for population size).
Lower burden in Vorarlberg: Dornbirn is the only district rated with “very low heat stress” (13 hot days, 17.7% over 65)
THE HEAT STRESS INDEX – AND ITS SIGNIFICANCE
The heat stress index combines the number of hot days with the proportion of residents aged over 65 to assess the level of heat-related stress in five categories. The aim is to provide early warnings to decision-makers—helping them implement targeted protective measures such as greening initiatives, awareness campaigns, or support services for older individuals.
In absolute terms, more older people live in cities. However, urban areas often show a comparatively high level of awareness about the issue. In Vienna, for example, numerous climate measures—such as street greening—have already been implemented, with more planned. By showing the relative share of the population over the age of 65, the map also aims to raise awareness in rural areas, where similar challenges may emerge in the future. “With the heat map, we also want to highlight that rural regions will face problems in the future as well, and that incentives should be created there too—for example, to develop a heat strategy,” Hannah Schuster from the Complexity Science Hub and WU Vienna explains.
WHY THIS REMAINS A CRITICAL ISSUE IN 2025
Current trends indicate that this summer will once again bring widespread and intense heat stress across Austria. At the same time, demographic shifts are accelerating, and within just a few years, many more regions will have a significantly more vulnerable age structure.
Research led by Schuster shows that each additional hot day increases mortality by 2.4% per 1,000 inhabitants.
In 2024, only 9.57% of districts (equivalent to 16.8% of municipalities) had populations with over 25% of residents aged 65 and older. By 2050, this figure is projected to rise sharply to 94.68%.
Moreover, heat waves—defined as a week with more than three hot days—nearly triple the risk of death compared to isolated hot days.
Further details are available in the study.
