Hurricane Nicholas has made landfall along the Texas coast, bringing the threat of up to 20 inches (50cm) of rainfall to parts of the Gulf Coast which have already been battered by storms this year.

Nicholas is the 14th named storm of the 2021 Atlantic hurricane season.

Nearly all of Texas’ coastline is under a tropical storm warning, which includes potential flash floods, power cuts, and storm surges.

Forecasters are most concerned about how much rainfall Nicholas could produce, especially in flood-prone Houston.

Authorities in the city have deployed high-water rescue vehicles throughout the city and erected barricades at more than 40 locations that tend to flood, mayor Sylvester Turner said.

“This city is very resilient. We know what we need to do. We know about preparing,” said Mr Turner, referencing four major flood events that have hit the Houston area in recent years, including devastating damage from Hurricane Harvey in 2017.

Harvey was blamed for at least 68 deaths, including 36 in the Houston area.

The Houston school district, the state’s largest, as well as others, announced that classes would be cancelled on Tuesday and Texas governor Greg Abbott says rescue teams have been deployed in case they are needed.

The weather threat also closed multiple COVID-19 testing and vaccination sites in the Houston and Corpus Christi areas, and forced the cancellation of a Harry Styles concert scheduled for Monday evening in Houston.

Six to 12 inches (15 to 30cm) of rain were expected along the middle and upper Texas coast, with isolated maximum amounts of 18 inches (46cm) possible.

Other parts of southeast Texas and south-central Louisiana and southern Mississippi could see four to eight inches (10 to 20cm) over the coming days.

President Joe Biden declared an emergency for Louisiana and ordered federal assistance to supplement local response efforts due to conditions resulting from Nicholas, the White House said.

A tornado or two may be possible Tuesday along the upper Texas and southwest Louisiana coast, according to the National Hurricane Center in Miami.

The worry with Nicholas will be how slowly it moves. Storms are moving slower in recent decades, and Nicholas could get stuck between two other weather systems, said hurricane researcher Jim Kossin of The Climate Service.

Louisiana Governor John Bel Edwards declared a state of emergency on Sunday night, ahead of the storm’s arrival in a state still recovering from Hurricane Ida, last year’s Hurricane Laura, and historic flooding.