Residents of Bermuda were urged to prepare to protect life and property ahead of Hurricane Paulette, which was forecast to become dangerous on Sunday.

At the same time, Tropical Storm Sally intensified in the Gulf of Mexico. That storm had maximum sustained winds of 50mph with higher gusts, forecasters said, adding that it was expected to strengthen into a hurricane on Monday and reach the US coast late that day or early on Tuesday.

A hurricane warning was issued from Grand Isle, Louisiana, to Ocean Springs, Mississippi, including metropolitan New Orleans. A storm surge warning and a tropical storm warning were also in effect for parts of the Gulf coast.

Paulette gained hurricane status late on Saturday and was expected to bring storm surge, coastal flooding and high winds to Bermuda, according to a US National Hurricane Center (NHC) advisory.

The storm had maximum sustained winds of 80mph as it strengthened along a curved course toward Bermuda. The biggest threats were strong winds, storm surge, up to 6in of rain and life-threatening surf and rip currents. The storm was 280 miles south-east of the British overseas territory on Sunday morning.

It was the strongest in terms of winds of six disturbances the center was tracking in the Atlantic and the Gulf of Mexico.

The Louisiana governor, John Bel Edwards, declared a state of emergency and officials in New Orleans issued a mandatory evacuation order for areas outside levee protection.

Storm surge was forecast to reach dangerous levels, due in part to the tide. Up to 11ft of water was predicted from the mouth of the Mississippi river to Ocean Springs, including Lake Borgne.

A slow moving storm, Sally could produce up to 20in of rain by the middle of the week, forecasters said. The system was moving west-north-west at 13mph and was centered 155 miles west of Port Charlotte, Florida and 300 miles east-south-east of the mouth of the Mississippi.

Heavy rain was battering south-western Florida, the NHC said.

Among other storms being tracked by forecasters, Rene was forecast to weaken further on Monday but Tropical Depression Twenty was expected to strengthen and become a tropical storm by Tuesday.