Half-metre of rainfall in Texas is just the start as Hurricane Patricia’s moisture adds to the mix.
Six people are known to have died as storms slam parts of the US.
The worst of the weather hit the southern state of Texas, where at least three tornadoes were reported.
The state was still recovering from an earlier battering of severe weather, when the remains of Hurricane Patricia swept across the region.
This led to flooding, power outages and cancelled flights. The ground was still saturated when the latest storms hit.
The rain on Friday and Saturday delivered as much as 8 mm of rain per hour, which fell onto water logged ground, leading to widespread flooding.
The Houston Fire Department said it had made more than 130 water rescues on Saturday, and some public light-rail and bus routes had to be suspended.
A number of tornadoes were also reported. One ripped through Brazoria County, 50 kilometres south of Houston, smashing a number of vehicles in a trailer park.
Just half an hour later, another tornado hit the Houston suburb of Friendswood, damaging a number of homes.
The weather system is now heading eastwards, and more severe weather could be seen in Louisiana, Mississippi and Alabama on Sunday.