Up to 19 cm in diameter

Hailstones are getting bigger and bigger in Europe

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(Bild: georgeion88 - stock.adobe.com)

What has been suspected for some time has now been clearly confirmed: Hailstones in Europe are indeed getting bigger and bigger. The current record is 19 centimetres in diameter!

For the European Severe Storm Laboratory (ESSL), which has a research and training center in Wiener Neustadt, 2023 is the third record-breaking hail season in a row. In addition to the pure number of reports, the number of days with large hailstones was also record-breaking. There were 229 days with large hail, 96 days with very large hail and 13 days with giant hail. The data extends up to 20 January 2024, meaning that there were a total of 9627 reports of hailstones larger than two centimetres last year. According to the International Severe Weather Research Institute, 1931 reports concerned very large hailstones (more than five centimetres) and 92 reports even concerned giant hailstones with a size of more than ten centimetres.

Records were again broken not only for the quantities of large and very large hail - but also for the maximum hail sizes. Europe's largest photographed hailstone was recorded twice in Italy within just five days. On July 19 last year, a hailstone with a diameter of 16 centimetres was reported, and on July 24 even one with a diameter of 19 centimetres.

The heaviest hailstone weighed 484 grams
In both cases, the hail sizes were estimated using reference objects placed near the hailstones, emphasizes ESSL. The heaviest officially weighed hailstone also fell on July 24, weighing 484 grams. The hailstone had a diameter of 13 centimeters. It is therefore assumed that the largest hailstones observed on July 19 or 24 probably weighed considerably more. In addition to Italy, other countries were also affected by huge hailstones. In Slovenia, the largest hailstones reached 13.8 centimetres in diameter, in Bulgaria and Croatia 13 centimetres each, in France, Spain and Bosnia eleven centimetres each and in Germany and Russia ten centimetres each.

Huge hailstones, mudslides, broken cars: severe storms hit the Alpine republic again this season.

(Bild: Krone KREATIV/ZOOM.TIROL APA (2))

Prolonged hailstorms
According to the ESSL, the fact that the number of reports was so high could also be due to the fact that data collection has become more efficient. Private observers - i.e. citizens - made a significant contribution to the reports. In addition, there were very long-lasting hailstorms in 2023, which produced large hailstones in many places. For comparison: In 2022, there were five hailstorms over a distance of more than 200 kilometers. In 2023, there were 13 such hailstorms, with one particularly long-lasting supercell producing a 686-kilometre-long hailstorm strip that affected as many as five countries.

The country with the most large hail reports was France with 1502 cases, closely followed by Italy with 1468 reports. In terms of the most devastating hailstorms, however, Italy led the way with 596 reports of very large hailstorms and 67 reports of huge hailstorms, compared to 280 and ten reports in France. The third most affected country by large hail was Germany with 1270 reports, 142 of which involved very large hail.

The damage is enormous
The resulting damage was enormous: at least 328 people were injured by hail, the actual figure is likely to be much higher. Most of the injured (242) were reported from Italy. Hail also caused enormous economic damage. According to reinsurer Munich-RE, hailstorms in Italy cost billions of US dollars, and the Gallagher-RE report put the figure at three billion US dollars (around 2.77 billion euros), with the total loss costs for the storms in Europe amounting to around twelve billion US dollars.

Twice as many hailstorms in Austria
Pieter Groenemeijer from ESSL reported on Wednesday on Ö1's "Morgenjournal" that the increase in severe hailstorms was mainly observed in the Alpine region. According to the report, the probability of hailstones with a diameter of five centimetres is 300 percent higher in northern Italy than it was before 1990. In Austria, the number of hailstorms has doubled, according to Groenemeijer, and this is particularly noticeable in the south of the country. The increase in hailstorms in Europe has to do with the warmer sea temperatures in the Mediterranean, reported Ö1. The evaporation causes more energy to enter the atmosphere, which rises in thunderclouds and creates strong updrafts. "The stronger the updraft, the larger the hail can become," said Groenemeijer on Ö1.