Hundreds rescued from flooding in US state of Texas

High waters have flooded neighbourhoods around Houston following heavy rains that have already resulted in crews rescuing more than 400 people from homes, rooftops and roads engulfed in murky water.

On Saturday, a wide region was swamped from Houston to rural East Texas, where game wardens rode airboats through waist-high waters rescuing both people and pets who did not evacuate in time.

One crew brought a family and three dogs aboard as rising waters surrounded their cars and home.

A flood watch was in effect through Sunday afternoon, as forecasters predicted additional rainfall Saturday night and the likelihood of major flooding.

"It’s going to keep rising this way,” said Miguel Flores Jr., of the northeast Houston neighbourhood of Kingwood. “We don’t know how much more. We’re just preparing for the worst.”

Friday's fierce storms forced numerous high-water rescues, including some from the rooftops of flooded homes. Officials redoubled urgent instructions for residents in low-lying areas to evacuate, warning the worst was still to come.

“A lull in heavy rain is expected through (Saturday) evening,” according to the National Weather Service. “The next round of heavy rainfall is expected late (Saturday) into Sunday.”

Up to 7.6 centimetres (3 inches) of additional rain was expected, with up to 12.7 centimetres (5 inches) possible in isolated areas.

Flood-prone area

Authorities in Houston have not reported any deaths or injuries.

The city of more than 2 million people is one of the most flood-prone metro areas in the country and has long experience dealing with devastating weather.

Hurricane Harvey in 2017 dumped historic rainfall that flooded thousands of homes and resulted in more than 60,000 rescues by government rescue personnel across Harris County.

Of particular concern was an area along the San Jacinto River, which was expected to continue rising as more rain falls and officials release water from a full reservoir.

Hidalgo issued a mandatory evacuation order on Thursday for people living along portions of the river.

The weather service reported that the river was at nearly 22.6 metres (74 feet) late Saturday morning after reaching nearly 23.7 metres (78 feet).

The rapidly changing forecast said the river was expected to fall to near flood stage of 17.6 metres (58 feet) by Thursday.