A worker (right) repairs a power line in Austin, Texas, the US, on Saturday. Photo: VCG

Tropical Storm Nicholas gained strength as it tracked up the Texas coast hours before its expected landfall late Monday, threatening to unleash a dangerous deluge of rainfall on the southern US state, meteorologists warned.

At 2100 GMT Nicholas was located some 115 kilometers south of Port O'Connor on the Gulf of Mexico, with Texas's largest city of Houston squarely in the storm's sights, according to the National Hurricane Center.

Packing maximum winds of 104 kilometers per hour, Nicholas was forecast to bring "life-threatening" flash flooding and storm surges when it barrels ashore, the Miami-based NHC said.

"Nicholas could be near hurricane strength when it reaches the central Texas coast," it added, with the storm's center due to move onshore Monday night.

Between 15-30 centimeters of total rainfall is expected to wallop parts of Texas and western Louisiana, with isolated maximum amounts of 45 centimeters.

"This rainfall may produce areas of considerable flash and urban flooding," the center said.

Texas Governor Greg Abbott urged state residents to comply with warnings and directions.

AFP