Mayor Bill de Blasio slammed Con Edison Monday morning as some 19,000 New Yorkers remained without power following a scorching weekend heat wave.

The blackout struck Sunday evening on one of the hottest days of the year with the mercury rising to the high 90s and the heat index reaching a sweltering 100 degrees, according to the National Weather Service. At its height, more than 50,000 Con Ed customers were left in the dark, with Brooklyn taking the biggest hit.

“I am extremely disappointed with Con Ed,” de Blasio said at a Monday press briefing at the Office of Emergency Management’s Interagency Command Center in Mill Basin. “I can’t trust them at this point because I’m not getting any real answers and they have let New Yorkers down once again.”

As outages peppered the area, Con Ed deliberately darkened some 33,000 customers in Brooklyn, mostly in Canarsie, Flatlands, Flatbush, Mill Basin, and Bergen Beach to stymie the strain on the overtaxed system.

“The concern was that we thought it was going to be a much wider outage, so to prevent more damage to the equipment we shut power off, thereby avoiding a much longer outage,” said Con Ed spokesperson Allen Drury.

Power was restored overnight to more than 30,000 customers. Those still in the dark in Brooklyn and Queens are not expected to have service fully restored until 7 p.m., according to Con Ed. Those without power in the Bronx will likely be back up and running by 1:30 p.m., and darkened customers in Manhattan will have power restored by 3 p.m., according to the utility company. Staten Island was not impacted by Sunday’s outages.

But the blackouts are unacceptable when “obviously this is a predictable situation and therefore preventable,” de Blasio charged. The mayor slammed the company for its lack of transparency and questioned the power company’s ability to run the city’s grid.

“It’s very clear we have to question whether Con Ed as it’s structured now can do the job going forward or whether we need to go to an entirely different approach,” de Blasio said. “I’m calling for a full investigation and further that we examine whether we need a new entity to handle the situation going forward because at this point I do not have a faith in Con Edison.”

On Friday, ahead of the city’s stifling heat wave, Public Advocate Jumaane Williams questioned the utility company’s spending on modernizing its infrastructure in a letter to the company’s president and CEO after the power grid’s relay protection system failed on July 13, triggering a five-hour power outage that impacted more than 200,000 city dwellers in the heart of Manhattan.

Con Ed, which is petitioning the New York Public Service Commission for a 8.6 percent electricity rate hike, delayed and ultimately scrapped a program to spent $350 million to modernize the very same relay protection systems that led to Manhattan’s recent blackout.

Con Ed says it has separately pumped $115 million into upgrading those systems, but New York State approves electricity and gas rates for public utilities based on their budgetary projections—meaning promises to upgrade infrastructure, that go unfilled, can play a major role in whether rate hikes are approved and passed on to New Yorkers.

“We are at a point where we really cannot trust Con Edison and they cannot keep asking for rate hikes if they cannot guarantee that their equipment will be up to par with the needs of New York City,” Williams said at a Friday press conference in Hell’s Kitchen.

Gov. Andrew Cuomo, who floated the possibility of revoking Con Ed’s license after Manhattan’s crippling blackout, also blasted the company for its lack of preparation, and said that 200 state troopers, 100 generators, and 50 light towers were sent to Brooklyn to assist during the latest outages.

“We have been through this situation with Con Ed time and again, and they should have been better prepared—period,” Cuomo said in a statement. “This was not a natural disaster; there is no excuse for what has happened in Brooklyn.”

The company, which is one of the country’s largest utility providers with 10 million customers in New York City and Westchester County, has warned of summer power outages, and Sunday’s blackouts were likely a preview of more of what’s to come as the city heads deeper into summer.