U.S. Sees 3 ‘Once in 1,000-Year’ Rains in a Single Week
These events are known as 1-in-1,000-year events because there is only a 0.1% chance that the amounts of rain that fell during the short timeframe would happen in a given year.

On August 2, southern Illinois received up to 14 inches of rain in 12 hours, a type of massive rain event that meteorologists say only happens approx once every 1,000 years. If this were the only event, it would still be newsworthy, but the rain in Illinois was actually the third such 1-in-1,000-year rain event in a period of one week.
Torrential rain and flooding after 14 inches of rain devastated parts of eastern Kentucky last week, killing at least 37 people, and flash flooding in the St. Louis area closed roads, trapped people in vehicles, and contributed to at least one death.
These events are known as 1-in-1,000-year events because there is only a 0.1% chance that the amounts of rain that fell during the short timeframe would happen in a given year.
Scientists say the climate crisis is increasing the frequency and likelihood of massive rain events, and our infrastructure makes the events that much worse because water isn’t able to permeate concrete and paved roads.