It's another hot, humid day on Long Island, but forecasters said rain -- possibly heavy at times -- finally enters the picture later in the week.

How hot is it on Tuesday? Record-breaking hot, with Long Island MacArthur Airport reaching 91 degrees as of around 1 p.m., surpassing the previous record of 89 set in 2010, the National Weather Service said.

Longtime records were also broken, with Central Park hitting 97, surpassing the previous record of 93 which was set in 1919, the weather service said. LaGuardia reached 94, up from the previous record of 91, set in 1945.

News 12 Long Island meteorologist Matt Hammer said the day looks mostly dry, hot and humid. And for children returning to school, "those classrooms without air-conditioning will be feeling brutal."

The rain comes late Wednesday, which again is mostly expected to be sunny and hot, with daily highs in the mid 80s, after a morning of patchy fog.

By late Wednesday and into Thursday morning, the chance for rain ranges from 20 to 70 percent.

"Overall, Wednesday will be OK," Hammer said. "Sunshine to start with increasing clouds."

There's a chance for an evening shower, "but otherwise the best chance comes on Thursday with a few scattered showers and thunderstorms."

The service said in a hazardous weather outlook that "showers and thunderstorms late Wednesday night through Thursday evening will be capable of producing heavy rain. There is a chance for flash flooding during this time frame."

Temperatures cool slightly after the rain moves off Long Island, Hammer said.

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The daily high for Friday is 80, and the weekend temperatures are similar, with a mix of sun and clouds, he said.

To combat the heat, the Town of Hempstead is opening its cooling centers through Wednesday, according to the office of Supervisor Kate Murray.