A comfortable Wednesday is set to give way to rising temperatures and humidity on Thursday.

And that’s just the prelude to a string of days with the potential to bring the area’s first official heat wave since 2013, says the National Weather Service.

“Humidity starts to increase a bit throughout the day tomorrow, but not to oppressive levels,” with highs around the mid-80s, said News 12 Long Island meteorologist Matt Hammer.

Then, get set to sizzle as for “Friday through the weekend the heat and humidity is back in full force,” Hammer said.

Highs of around 88, 92, 89, and 91 were in the forecast for Friday through Monday at Long Island MacArthur Airport, said Mike Silva, weather service meteorologist based in Upton.

By definition, a heat wave means at least three days in a row of 90 degrees or above.

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Temperatures may be several degrees cooler east of the William Floyd Parkway, Silva said, but conditions overall are expected to be muggy.

Of those four days, Monday was likely to edge out slightly the others as to having potential for being the most oppressive, thanks to the humidity, he said.

As for temperatures, the last time the airport saw a heat wave — and it was a real beauty — was from July 14 to 20 in 2013, according to data from the Northeast Regional Climate Center, based at Cornell University. That holds the record for the longest stretch of 90s since records started being kept in 1984.