Map Shows Alarming Increase in Heat Days in Austria

According to this, only three districts recorded a "very high" heat stress index in 2023, but by 2024 it was already 25. In 49 districts, there were at least 34 heat days, significantly more than in the peak year of 2019 (15 districts).

The team led by Hannah Schuster from the Complexity Science Hub (CSH) Vienna and the Vienna University of Economics and Business (WU) has updated the representation of heat stress, first presented last year, with data for 2024. The interactive map shows a heat index for all districts and municipalities based on the number of heat days (over 30 degrees Celsius). Additionally, a five-level heat stress index (from "very low" to "very high") can be read, which also takes into account the proportion of older people (over 65 years).

For the year 2023, the map shows the districts of Hollabrunn, Rust, and Eisenstadt-Raum in deep red - indicating a "very high" heat stress index. Last year, a span of 25 districts and statutory cities stretched from the eastern Waldviertel over the northern Weinviertel towards Burgenland, the industrial district, and the Mürztal to southern Styria and large parts of Carinthia, where all administrative units except Klagenfurt and Villach City and the district of Hermagor are marked in dark red. This color represents the highest heat stress index.

"Very high" is the heat stress index according to the study's definition if there are more than 27.6 heat days per year in the respective district and more than 22.8 percent of the population is older than 65 years. In contrast, the risk is "very low" if there are fewer than 14.9 heat days per year and the proportion of those over 65 is below 18 percent.

In terms of the number of heat days, in 2024, all districts in Burgenland had a "very high" heat index (more than 34 heat days), and in Lower Austria, this applied to 20 of the 24 districts or statutory cities. Due to the high number of heat days and the higher proportion of older people, the heat stress index was "very high" in seven of the ten Carinthian districts.

There are significant differences between Western and Eastern Austria: Examples of the significantly higher number of hot days and tropical nights (over 20 degrees Celsius) in the east are Rust and Neusiedl with 52 hot days each, or Wiener Neustadt (50) in contrast to Reutte (2).

2024 was sweltering in Vienna with 49 hot days and 41 tropical nights, with some districts like Wieden, Margareten, and Mariahilf experiencing up to 53 tropical nights. However, the heat stress index was not as pronounced due to the relatively young population (only 16.4 percent over 65 years).

Besides Vienna, the most tropical nights were recorded in Eisenstadt (33) and Rust (27). In contrast, residents of the districts Hermagor, Spittal an der Drau, Salzburg, Hallein, Sankt Johann im Pongau, Tamsweg, Zell am See, Leoben, Murtal, and all districts of Tyrol enjoyed restful sleep, as temperatures there never climbed above 20 degrees Celsius at night. The only district in Austria with a "very low" heat stress index was Dornbirn with 13 hot days and a proportion of 17.7 percent over 65-year-olds.

The scientists from CSH assume that this year's summer "will very likely bring strong heat stress again - and more widespread than in previous years." Additionally, demographic change is progressive, and in a few years, significantly more regions will have a high proportion of older - and thus more vulnerable - people: While in 2024 only about ten percent of the districts had a senior population of over 25 percent, by 2050, according to forecasts, it will be 95 percent.

This is problematic insofar as, according to the research team, each additional hot day mortality increases by 2.4 percent per 1,000 inhabitants. Heatwaves, meaning a week with more than three hot days, triple the mortality risk compared to individual hot days.

This article has been automatically translated, read the original article here .