Millions of people in Texas awoke on Wednesday without heat again following a historic winter storm that has killed 21 people so far, as icy conditions threatened to plague the country’s largest state.

Some 2.7 million Texas households were still without power, according to the Electric Reliability Council of Texas (Ercot), a cooperative responsible for 90 per cent of the state’s electricity. Ercot said 600,000 households had power restored overnight.

Laura Nowell, a 45-year old mother of four in Waco, Texas, said her family has been without electricity since before dawn on Monday and has been trying to keep warm by bundling up and running and sitting in their car.