Winter Storm and Texas Power Outage Map

Millions more are facing the freezing cold without heat, as grid operators have been forced to cut power on a rolling basis to avoid wider blackouts.

In Texas, the hardest-hit state, more than 3 million homes and businesses remained without electricity on Tuesday evening, according to PowerOutage.us, which aggregates live power data from utilities, down from 4.4 million earlier in the day. Hundreds of thousands of electricity customers in other states were also without power.

Controlled power outages began overnight on Sunday and into Monday in Texas, as the state’s grid operator sought to balance a surge in demand and a shortage of supply.

Just as electricity use soared — with Texans looking to beat back the cold by turning up their heaters — the state lost a portion of its generating capacity. Some natural gas and coal plants were knocked offline by the cold, and icy conditions stymied wind turbines too.

“This is certainly a freak anomaly storm,” said Thomas Overbye, a professor of electrical and computer engineering at Texas A&M University in College Station, Texas. “A lot of our thermal plants, our natural gas plants, are not set up to deal with this sort of cold.”

“How much the generation should be prepared for these sorts of temperatures is something I’m sure will be investigated very shortly,” Dr. Overbye said. But “the key right now is to get as much generation back online as possible.”