Storms have dumped half a metre of rain in the Houston, the US's fourth-largest city, flooding dozens of neighbourhoods and leaving at least five people dead.
Flash flooding and more rain are possible on Tuesday, a day after some areas saw water levels approaching 51 centimetres.
Scores of subdivisions flooded, schools and businesses were closed, and power was knocked out to thousands of residents who were urged to shelter in place.
Heavy flooding has become nearly an annual rite of passage in the practically sea-level city, where experts have long warned of the potential for catastrophe.
In addition to its location, Houston's "gumbo" soft soil, fast-growing population and building boom that has turned empty pastures into housing developments all over the city's suburbs and exurbs make it vulnerable to high waters, experts say.
