HOUSTON, TEXAS -- Houston area residents affected by deadly storms last week that left at least seven dead were finally getting some good news as officials said they expected power to be restored by Sunday evening to a majority of the hundreds of thousands still in the dark and without air conditioning amid hot and humid weather.

The widespread destruction of Thursday's storms brought much of Houston to a standstill. Thunderstorms and hurricane-force winds tore through the city -- reducing businesses and other structures to piles of debris, uprooting trees and shattering glass from downtown skyscrapers. A tornado also touched down near the northwest Houston suburb of Cypress.

More than 352,000 homes and businesses in Texas remained without electricity Sunday morning, with most of those in the Houston area.

"It's been a madhouse out here," Cypress resident Hallie O'Bannon said. "You know we don't have any power. No hot water. It's been really crazy."

At one of five cooling centres for people still without power in their homes, residents took shelter from the heat at a community centre in the Cloverleaf neighbourhood.

Carolina Sierra and her six-year-old son, Derek, enjoyed the air conditioning for a couple of hours Sunday. She said they have been without electricity since the storm hit Thursday, and their home has been stifling.

Derek passed the time colouring a picture of a dragon while his mother charged her cellphone and a portable lamp they planned to use Sunday night if the power was still not restored. Sierra, 38, said she gives her son multiple baths to try to keep him cool but he tosses and turns at night and struggles to sleep.

"We are desperate. We hardly sleep at night because of the heat," Sierra said.

Harris County Commissioner Adrian Garcia stood outside the centre Sunday, helping load water and ice onto vehicles while offering words of encouragement to residents still waiting for power to be restored.

"We are seeing a bit of the recovery come through. But we can't see enough of it fast enough," Garcia said.

Help was also on the way in the form of disaster assistance from the Federal Emergency Management Agency and loans from the Small Business Administration, said Harris County Judge Lina Hidalgo, the top elected official in the county where Houston is located. The federal assistance, which can help pay for temporary housing and repairs, will help residents affected by last week's storms as well as by flooding from heavy rainfall in late April and early May in parts of Houston, Harris County and several counties north of Houston.

CenterPoint Energy said it anticipated that about 80 per cent of affected customers in the Houston area would have service restored by Sunday evening. Hidalgo said 90 per cent of customers could be restored by Wednesday.

More than 4,600 customers remained without power Sunday morning in Louisiana, which had also been hit by strong winds and a suspected tornado.

CenterPoint Energy said 2,000 employees and more than 5,000 contractors were working in the Houston area to restore power.

"We understand the higher temperatures we are experiencing across Houston and surrounding communities make getting the lights and air conditioning back on even more important," Lynnae Wilson, CenterPoint's senior vice president of electric business, said in a statement.

Residents broke into cheers as lights and air conditioning kicked on at the eight-story Houston Heights Tower, a senior housing facility, Sunday morning. The nearly 200 residents had been living on emergency power since Thursday evening, with generators providing enough electricity to run just one of the building's elevators and a handful of fans in the community room, leaving apartments in darkness.

Volunteers and city workers had been ensuring residents received a steady supply of water, food and essentials like toilet paper.

"It just goes to show you how people come together," 72-year-old resident Joseph Torregrossa said, choking back tears.

The National Weather Service said in a post on the social media site X that residents should expect "sunny, hot and increasingly humid days" in the Houston area. Highs of about 90 degrees (32 Celsius) were expected this week, with heat indexes likely approaching 102 degrees (39 Celsius) by midweek.

With the temperature at 91 degrees (33 Celsius) Sunday afternoon, Lisa Reed sat in a folding chair outside her home in the Cloverleaf neighbourhood because she was still without electricity. A volunteer crew had just cut up a large tree in her front yard that had come crashing down on two vehicles in her driveway and stacked the wood neatly in two large piles.

Reed, 54, said no home on her street -- where branches and other debris were piled along the sidewalk -- escaped damage from last week's storms.

"It's nothing I can do," said Reed, a fifth grade teacher. "Take it all in stride. I'm a firm believer that God will work it all out."

Houston area school districts canceled classes for more than 400,000 students Friday. The Houston Independent School District, the state's largest, said power had been restored to nearly 200 campuses and those schools would be open Monday. But another 77 campuses remained without power.