As more than 30 centimeters of rain deluged the nation's fourth-largest city, inundating homes, shutting down highways and leaving at least five people dead, Houston's mayor said there was no immediate solution.

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.

"I regret anyone whose home is flooded again," said Sylvester Turner, the city's mayor, on Monday. "There's nothing I can say that's going to ease your frustration. We certainly can't control the weather."