Tropical storm Beryl could grow into a Category 2 hurricane by the time it makes landfall in the Houston area early on Monday as it regains strength moving northwest over the Gulf of Mexico, according to the U.S. National Hurricane Center (NHC).

The storm was expected to strengthen into a Category 1 hurricane on Sunday as it travels over warm waters. The NHC issued hurricane warnings across much of the Texas coast.

Forecasters warned that Beryl could bring punishing winds and 13 to 25 centimetres of rain to the Texas coast and beyond.

Coastal areas were already seeing waters rise on Sunday and county officials ordered one beach town evacuated. The U.S. Coast Guard shut the port of Houston on Sunday afternoon due to worsening sea conditions. It also closed the ports of Texas City, Freeport and Galveston.

School systems including Houston's — the state's largest — said they would be closed Monday.

NHC Director Michael Brennan warned on Sunday afternoon that residents had only a few more hours to prepare. "If you have been asked to leave by local officials, please do so," he said.

Acting Texas Gov. Dan Patrick said Beryl "will be a deadly storm for people who are directly in that path." He declared 120 counties to be in a disaster area.

The storm has prompted closures or vessel traffic restrictions at multiple ports in cities from Houston to Corpus Christi, which is the top crude oil export hub in the U.S. The closures could disrupt crude oil exports, shipments of crude to refineries, and motor fuel from these plants.

Temperatures in the region are forecast at above 32 C in the coming days, including heat indices as high as 42 C on Sunday. Parts of eastern Texas were on flood watch ahead of the storm, which had maximum wind speeds of 96 km/h as of Sunday morning.

Earlier this week, the storm — which at one point intensified into the earliest Category 5 hurricane on record — left a deadly trail of destruction across the Caribbean. It swept through Jamaica, Grenada and St. Vincent and the Grenadines in addition to unleashing heavy rainfall on northern Venezuela.

The storm has killed at least 11 people, torn apart buildings and felled power lines and trees.

Beryl last made landfall on Friday, crossing Mexico's Yucatan Peninsula and causing power outages in some areas. It largely spared the top beach destinations there and caused no casualties. Video showed the international airport at Cancun packed with tourists on Saturday as they rescheduled flights home after the storm.

With Beryl now approaching Texas, the U.S. National Weather Service warned of storm surges causing coastal flooding and rip currents.