Three days after a devastating thunderstorm tore through Houston, the nation’s fourth most populous city began lurching back onto its feet on Sunday.

Power returned to hundreds of thousands of homes but still remained out across hard-hit areas not far from downtown. Traffic crawled through blackened intersections or down neighborhood streets now lined with limbs and leaves piled up like green-brown snow banks.

Clear skies helped dry out the sopping city over the weekend but also presented a new danger as temperatures climbed to around 90 degrees and were expected to stay. More than 350,000 electrical customers across huge swathes of Houston and its northwest suburbs started the day without service, cutting off the air conditioning that helps make the Gulf Coast heat bearable.

“We can’t sleep,” said Dolores Valladares, 61, with sweat on her brow as she sat outside her home in the city’s East End, watching her grandchildren.

Inside was even more stifling. Her food had spoiled, and she has struggled to get a reimbursement for her food stamps. Instead, she has been relying on nearby fast food chains that have power for cheap food and cool air.

The local electric company, CenterPoint Energy, has been racing to repair lines that had fallen from the force of the wind or under the weight of trees, saying it had done so for more than a half-million customers within 48 hours of the storm on Thursday evening. A quarter of a million were fixed from Saturday into Sunday.