Powerful winds and rain approached Texas on Sunday morning as Beryl was expected to turn back from a tropical storm into a hurricane overnight and pound a long stretch of coast with heavy downpours, howling gusts and dangerous storm surge.

A long stretch of the Texas shoreline was under a hurricane warning as Beryl’s outer bands were forecast to begin lashing the coast Sunday.

Texas officials are telling coastal residents to expect power outages and flooding.

Landfall was expected early on Monday and officials in several coastal counties issued voluntary evacuation orders while urging tourists along the beach for the Fourth of the July holiday to leave.

The earliest storm to develop into a Category 5 hurricane in the Atlantic, Beryl caused at least 11 deaths as it passed through the Caribbean earlier in the week. A storm surge was fuelled by the Atlantic’s record warmth.

“We’re seeing the outer bands of Beryl approach the Texas coast now and the weather should be going downhill especially this afternoon and evening,” Eric Blake, a senior hurricane specialist with the National Hurricane Centre, said on Sunday morning.

“People should definitely be in their safe space by nightfall and we’re expecting the hurricane to make landfall somewhere in the middle Texas coast overnight.”

Texas officials warned people along the entire coastline to prepare for possible flooding, heavy rain and wind. The hurricane warning extended from Baffin Bay, south of Corpus Christi, to Sargent, south of Houston.

In Corpus Christi, officials asked visitors to cut their trips short and return home early if possible. Residents were advised to secure homes by boarding up windows if necessary and using sandbags to guard against possible flooding.

Ben Koutsoumbaris, general manager of Island Market on Corpus Christi’s Padre Island, said there has been “definitely a lot of buzz about the incoming storm,” with customers stocking up on food and drinks, particularly meat and beer.

The White House said on Sunday that the Federal Emergency Management Agency had sent emergency responders, search-and-rescue teams, bottled water and other resources along the coast.

Some coastal cities called for voluntary evacuations in low-lying areas that are prone to flooding, banned beach camping and urged tourists travelling on the Fourth of July holiday weekend to move recreational vehicles from coastal parks.

In Refugio County, north of Corpus Christi, officials issued a mandatory evacuation order for its 6,700 residents.

Lt Gov Dan Patrick, who is acting governor while Greg Abbott is travelling in Taiwan, issued a pre-emptive disaster declaration for 121 counties.

“Beryl is a determined storm, and incoming winds and potential flooding will pose a serious threat to Texans who are in Beryl’s path at landfall and as it makes its way across the state for the following 24 hours,” Mr Patrick said on Saturday in a statement.

Beryl earlier this week battered Mexico as a Category 2 hurricane, toppling trees but causing no injuries or deaths before weakening to a tropical storm as it moved across the Yucatan Peninsula.