According to the UN weather organization WMO, the longest lightning bolt ever measured stretched over 768 kilometers. The discharge occurred in April 2020 between the US states of Texas, Louisiana and Mississippi. This roughly corresponds to the distance between Rostock and Lake Constance. After scientific verification, the record was confirmed on Tuesday in Geneva. In addition, the WMO declared a 17.1-second mega-flash over Uruguay and northern Argentina in June 2020 as the longest-duration flash.
Both records occurred in so-called mesoscale convective systems, which form when thunderstorms combine to form a large thunderstorm complex. The previous record holders were a 709-kilometer flash over southern Brazil in October 2018 and a 16.73-second flash over northern Argentina in March 2019.
“Lightning is a major hazard that claims many lives each year,” said WMO Secretary-General Petteri Taalas. On the occasion of the records, the UN organization emphasized that lightning can discharge over extremely long distances. If a thunderstorm is ten kilometers away, people should seek shelter in solid buildings or closed vehicles, because lightning can then strike within a few seconds.