The rain fell for days, sometimes 3 inches or more in a single hour, as streets became rivers and rivers ate up entire neighborhoods in southeast Louisiana.
Between Aug. 11 and Aug. 14, more than 20 inches of rain fell in and around East Baton Rouge, one of the hardest-hit parishes. And in some parishes in the region, as much as 2 feet of rain fell in 48 hours.
The National Weather Service says the likelihood that so much rain would fall in so little time was about one-tenth of 1 percent. A flood this bad should only happen once every thousand years.