Flood in Hamburg, 17.02.1962; picture by Oxfordian Kissuth (own work). Licensed under CC BY-SA 3.0, via Wikimedia Commons, https://commons.wikimedia.org/wiki/File%3AHamburg_-_Flutkatastrophe_1962.jpg
In the night of 16 to 17 February 1962 the hurricane Vinicinette caused a storm flood at the North Sea coast of Germany. Hamburg was affected especially hard, the early warning systems failed and the danger wasn’t taken seriously. The residents of Hamburg were surprised by the water in their sleep. 315 people died in the city alone (of 340 people in total).
Documents that might have helped genealogists today were destroyed as well. The public record office itself was left unharmed, but the records of some administrative bodies were affected. It’s hard to estimate, how many records of private companies were lost as well. If one of your ancestors worked in any of those affected companies prior to 1962, it might be hard to find information today.
Flooded… Catastrophic influences on genealogy