What the F°?

If New Yorkers ran out of polite words to describe how hot it got on Saturday, they’re gonna be speechless on Sunday.

On the hottest day since 2011, official temperatures Saturday reached a record-matching 96 degrees at Kennedy airport. But the “heat index” — which combines temperature and humidity — soared to 110 degrees, the National Weather Service reported.

Sunday’s heat in New York could again approach record temperatures, with the forecast for 100 degrees, and a heat index of 105 to 107 degrees.

It is hotter on the streets.

Unscientific measurements by The Post Saturday showed the mercury at 110 degrees in Union Square. At the basketball court on West 3rd Street and 6th Avenue in Greenwich Village, the pavement was a sneaker-melting 122 degrees. And in the Thomas Greene playground in Gowanus, Brooklyn, the rubber bedding surged to a perilous 155 degrees.

The disparity from official temps can be attributed to the “heat island” effect. The Weather Service places official thermometers in grassy areas, protected from direct sunlight. The air on the streets, meanwhile, is much hotter because asphalt, concrete and glass buildings absorb heat from direct sunlight. City spaces can be far hotter than what weather services report.

New Yorkers could feel the difference.

At McCarren Park Pool in Brooklyn, Mayor de Blasio shook hands with kids and warned everyone to stay hydrated. The pool was packed to its 1,500-person capacity, and long lines formed.

Tamara Wright, 31, a correction officer, was there from Far Rockaway with three kids because they wanted to avoid the hot sand on the beach.

“We have been waiting for over 45 minutes,” Wright said. “It’s too hot to be standing out here. If I knew the line would be this long, I would have never come.”

The heat felled a firefighter battling a two-alarm house fire in Jamaica. He was hospitalized.

EMS logged at least 88 calls for heat exhaustion.

But the city dodged a sweaty bullet.

There were sporadic outages.

Con Edison said only about 2,900 customers had no electricity. In the Rockaways, PSEG reported 2,000 outages.

City Correction officials said that some 3,700 inmates in the two jails without air-conditioning — Brooklyn Detention Complex and Otis Bantum Correctional Center on Rikers — were being provided with fans, ice, water and frequent cool showers.

Transit officials reported no significant delays, although subway-platform temps soared.

The break here will come late Sunday, when showers or thunderstorms are expected. A cold front will reach the region on Monday, and more storms, some strong, settling in on Monday afternoon.

Here is how New Yorkers weathered Saturday: