GeoSphere Austria Heat Balance Report, June 2026: A heatwave for the record books
With the arrival of thunderstorms and a significant drop in temperature on Wednesday evening in eastern Austria, a fortnight-long heatwave has come to an end – one that not only shattered previous June records but also broke all-time records one after another. Rarely before have extreme temperatures, which even reached or just exceeded the 40-degree mark, spread so extensively across the country.
157 of GeoSphere Austria’s 277 weather stations set new records for the absolute maximum temperature for the month of June. Of these 157 stations, 112 have a time series spanning more than 30 years. At 45 of these 157 stations, temperatures have been recorded daily for at least 80 years. ‘What is remarkable about the new June records is that they did not simply beat the old ones by a few tenths of a degree,’ emphasises climatologist Alexander Orlik of GeoSphere Austria. On average, the new maximum temperatures for June 2026 exceeded the previous records by 1.4 degrees. At 46 stations, the increase was as much as two degrees or more. ‘At the Hohe Warte in Vienna, where daily maximum temperatures have been recorded since 1872, the previous June record of 36.1 degrees from 1950 was surpassed by a full 3.6 degrees. The annual record of 38.5 degrees from August 2013 was also significantly lower than the new record of 39.7 degrees,’ adds Orlik.
In total, a new annual record was set at 66 weather stations. 40 of these have been recording maximum temperatures for 30 years, and 16 for at least 80 years. With the onset of the heatwave on 18 June 2026, the 35-degree mark was reached or exceeded at around half of all 277 GeoSphere Austria weather stations. A daily maximum of 38 degrees was recorded at 46 stations, and 39 degrees or more at 15 stations. Orlik: ‘What made this extremely hot spell in June so challenging, however, was not just the daily maximum temperatures of up to 40 degrees, but also the length of the heatwave, which had gripped the whole of Austria.’ Depending on the region, there were between ten and 14 consecutive ‘heat days’ – defined as days with temperatures of at least 30 degrees – at altitudes below 800 metres above sea level. ‘Such conditions have never before occurred on a nationwide scale in June,’ added climatologist Orlik.
There was also significant heat stress during the night. In many places, the air temperature did not fall below 20 degrees (tropical night). The first tropical nights occurred sporadically on 17 June; by 22 June, 35 weather stations had already recorded tropical nights. The phenomenon was most widespread during the night of 28 to 29 June, when the air temperature at 94 GeoSphere Austria weather stations did not fall below 20 degrees. Comparable nights with such a widespread occurrence of tropical nights were only recorded on 4 August 2017 and 30 June 2024. The previous Austrian record for the warmest night was also broken: on the night of 29 June, the minimum air temperature at the Jubiläumswarte in Vienna (450 metres above sea level) reached just 27.3 degrees. The previous record stood at 26.9 degrees and was set on 2 August 2017.
The spell of hot weather came to an end in Vorarlberg, Tyrol, Salzburg and Upper Austria on Tuesday (30 June). In Lower Austria, Vienna, Burgenland, Styria and Carinthia, temperatures will once again exceed the 30-degree mark on Wednesday (1 July), at least in some parts of the country.
‘The heatwave in June 2026 ranks among the top five most severe heatwaves since records began in all provincial capitals,’ explains Orlik. In Bregenz, Innsbruck, Vienna (Hohe Warte) and Linz (the latter jointly with 2015), it was the most severe.
A cool respite in the mountains? Quite the opposite: ‘In the high mountains, it was only seemingly cold. For the second half of June, the air temperature was around five degrees above the 1991–2020 climate average and as much as seven degrees above the significantly colder 1961–1990 climate average,’ Orlik explains. At the Hoher Sonnblick, at 3,109 metres above sea level, the average daily maximum during the heatwave was ten degrees and the average daily minimum was 4.5 degrees. These are new record highs in the observatory’s history of measurements, where June figures have been recorded since 1887.
The current heatwave is also consistent with the long-term trend towards more extreme heat as a result of climate change. A trend analysis of the longest heatwaves in the state capitals shows that, in today’s climate, the most severe heatwaves last on average around seven days longer than they did around 1960, which corresponds to an increase of around 140 per cent. Widespread analyses using the SPARTACUS dataset also show a significant increase, for the period 2016 to 2025 compared with 1961 to 1990, in the number of extreme heat days with temperatures of at least 35 degrees and tropical nights with temperatures not falling below 20 degrees — particularly in the eastern lowlands and at lower altitudes in the west. This means that not only is the likelihood of individual record-breaking days increasing, but so too is the particularly stressful combination of prolonged periods of very hot days and warm nights.
Translated with DeepL.com (free version)