As the storm reached land at 05:30 GMT, it was upgraded to a hurricane, but weakened after landfall.

Over 500,000 power outages have been reported in Texas, according to PowerOutage.us, the report said.

The heavy rainfall has exposed the region to the risk of life-threatening flooding.

Nicholas is carrying maximum sustained winds of 70mph (110km/h), weather officials said, according to the report.

It is expected to hit the Texas coast and upper Louisiana with five to 10 inches of rain.

However, rainfall of up to 20 inches could lash central to southern Louisiana, they said.

The US National Hurricane Centre said that Nicholas "has continued to move slowly inland and has weakened during the past few hours" but cautioned against possible "life-threatening flash flooding impacts, especially in highly urbanised metropolitan areas," while the National Weather Service called it a "life-threatening situation", according to BBC.

"We want to make sure that no one is caught off guard by this storm," Louisiana Governor John Bel Edwards told a news conference.

He warned that the situation could worsen as drainage systems are still clogged from Ida and could trigger flash floods.

More than 119,000 homes and businesses are still without power in Louisiana due to Ida, he added.

In wake of the heavy rains, Texas Governor Greg Abott said swift-water boats, helicopters & high profile vehicles to help local authorities with rescue efforts arising from flooding & high winds to hrlp loval authorities. Emergency shelters have been also set up for displaced residents.