Widespread power outages in the Texas capital stretched into a third day for thousands of residents following a winter storm that was spiralling into a management crisis as city leaders remained unable to say when all the lights would come back on.

Impatience among frazzled, freezing and fed-up families in Austin escalated even as milder weather returned. On Friday, the newly elected mayor stood before cameras and apologised after a week of slow repairs, failed technology and lacking communication with the public. “The city let its citizens down. The situation is unacceptable to the community, and it's unacceptable to me,” said Mayor Kirk Watson, a Democrat who took office in January. “And I’m sorry”.