Service had been restored to most of the 19,000 Staten Island customers who lost power in the heat by Tuesday morning, Con Edison reported. Only about 175 customers were still without electricity. 

A power outage due to equipment failure at about 2 p.m. on Monday was most likely caused by the extreme heat, and knocked out power to about 19,000 customers. The areas where customers were without power included St. George, New Brighton, Tompkinsville, Stapleton, Mariners Harbor, and Travis, said Philip O'Brien, a spokesman for Con Edison.

A heat advisory was in effect until 6 p.m. Monday, with the high for the day expected to be well into the 90s. It's the hottest day of the year so far. 

A total of 36 NYPD traffic agents and supervisors were headed to Staten Island on Monday night to manage the evening commute. Police were also placing 24 light towers at "critical intersections and locations including Hylan Blvd. and Father Capodanno Blvd.," according to the mayor's office.

Customers in the affected Staten Island areas that didn't lose power were experiencing a 5% reduction in the voltage, O'Brien said. Richmond Hill in Queens, and an area west of Times Square were experiencing a reduction of 8%.

It was not immediately clear when power would be restored to customers on Staten Island. Con Ed was transporting eight generators -- three are already there -- to support the affected areas.

The city's Office of Emergency Management was extending the hours of operation for three cooling centers on Staten Island until 11PM: the Todt Hill Community Center, the Richmond Terrace Community Center, and the West Brighton Community Center. MTA buses were also being brought in to help provide air conditioning.