NEW YORK — Another heat wave was rolling into the New York tristate region Sunday as over 300,000 residents and businesses waited for electricity to return after last week’s tropical storm.

The race to restore fuel for desperately needed air conditioners, refrigerators and electronic devices as another work week approached was in full swing under sunny skies as thousands of power company workers tried to restore energy before temperatures lurch toward 90 degrees on Monday.

The power restoration was made more urgent by the pandemic that has turned homes into work places for many.

The National Weather Service issued a heat alert Sunday, saying temperatures from noon Monday until 8 p.m. Wednesday would create conditions that “are dangerous to health," particularly for anyone without air conditioning, older adults, and people with chronic health conditions.

Utility companies said they were doing the best they can to repair damage left behind by Tropical Storm Isaias, which temporarily wiped out power to over 2.5 million customers in New York, New Jersey and Connecticut.

By Sunday, hundreds of thousands of residents and businesses remained without power although utilities said crews had restored power to most who were left in the dark.

Eversource Connecticut said it had restored service to 741,000 customers and expected 90% of its clients to have power by Sunday evening. But its online map of communities showed that most communities would not be fully restored until Monday or Tuesday.

It said about 140,000 customers among its 1.3 million customer base remained without service despite help with repairs from 2,300 line crews from 12 states and Canada.

Craig Hallstrom, Eversource’s president of regional electric operations, said the 27 polling locations out of 540 polling spots statewide that were without power would be restored by Tuesday's elections.

Connecticut Gov. Ned Lamont, speaking on CBS' “Face the Nation," on Sunday said the COVID-19 pandemic had impacted recovery efforts, including hiring restoration crews from state's currently on the Connecticut, New York and New Jersey quarantine list.

“In the middle of a COVID pandemic, ‘Hey, I got a quarantine on people from South Carolina, (but) please come on up and fix our wires,’” he said. “But we’re getting people tested and we’re fixing the wires. Number one safety, we’ve got to get electricity back on.”

Lamont said all those out-of-state line workers are considered essential and are not being subjected to the 14-day quarantine.

PSEG on Long Island reported steady progress Saturday but said 60,000 of its 420,000 storm-affected customers were without power as Sunday arrived.

“While we have made steady progress, we are finding that each job is requiring more work than anticipated due to the extent of the storm’s damage. The more than 5,000 fallen trees or large limbs reported have contributed to the amount of work required to bring customers back," the company said in a statement.

It added that power to some customers would not be restored until Monday.

Nassau County Executive Laura Curran called the rate of restorations on Long Island unacceptable.

New York Sen. Charles Schumer said he told the head of the utility Sunday that nearly a week was too long to wait for restoration of power, particularly for vulnerable populations like the elderly and sick.

About 45,000 customers of several utilities in New Jersey remained without power Sunday.

Con Edison said nearly all of its New York City customers would be restored by the end of Sunday while some in Westchester County would not be fixed until Monday.

About 300,000 Con Edison customers lost power in the storm in New York City and its northern suburbs and the company said 65,000 awaited repairs Sunday, including 35,000 in Westchester County and 11,000 in Queens.

Associated Press Writer Pat Eaton-Robb in Columbia, Conn., contributed to this story.