An ongoing heat wave has knocked out power to thousands of Con Edison customers in the five boroughs over the past two days.

As of 6:30 p.m. Tuesday, 3,521 customers in the city were without power, including 1,290 in Queens, 1,513 in Brooklyn, 80 in the Bronx and 47 on Staten Island, according to Con Edison's outage map.

The utility said its crews are working around the clock in “sweltering temperatures” and have already restored power to more than 37,000 customers in the Bronx alone since the heat wave began.

Power outages began Monday, with more than 12,000 Con Edison customers impacted at one point. By 8:30 p.m. Monday, more than 8,300 customers on Staten Island were in the dark, along with about 1,880 in the Bronx, more than 1,300 in Queens and two in Manhattan. (A "customer" outage does not necessarily reflect one resident or household. For example, in some instances, a "customer" outage could reflect an entire residential building.)

On Monday morning, Con Edison reduced voltage by 8% in parts of southeast Queens to support repairs. By Monday afternoon, similar voltage reductions were in effect on parts of Staten Island and in several Brooklyn neighborhoods.

Con Edison is urging residents in certain neighborhoods to avoid using energy-intensive appliances such as washers, dryers and microwaves, and to hold off on charging electric vehicles.

On Tuesday, Con Edison president Matthew Ketschke appeared on “Mornings On 1” and emphasized the need for conservation. Because most of the city’s electrical infrastructure is underground, he said, it’s especially vulnerable to overheating during intense summer heat.

While acknowledging the heat, the company did also ask residents to curb “unnecessary use of air conditioning.”

“If you have two air conditioners, use only one and set it to the highest comfortable temperature,” it advised.

An Extreme Heat Warning is in effect for the city through Tuesday night.

The city has opened cooling centers across the five boroughs. Find one near you here.