Lets say there are 10,000 weather stations on the Earth. The odds of each one having a 100 year flood in a given year are 100:1. That means that we would expect to have a one hundred year flood somewhere on earth one hundred (10,000/100) times a year – or about once every three or four days.
A 500 year flood would occur somewhere on earth about once every two or three weeks, on average.
Alarmists make big headlines over completely ordinary events, because they are statistical mental midgets.