A heat advisory remains in effect for Long Island until Wednesday night as hot and humid conditions will continue with temperatures soaring into the upper 90s, the National Weather Service said.

Suffolk County is forecast to experience highs in the mid-90s, while areas closer to New York City, including Nassau County, will see highs in the upper 90.

Long Island was under an extreme heat advisory on Tuesday due to the heat value index reaching 105 degrees or higher, the service said.

While temperatures are dropping slightly on Wednesday, heat value indexes remain unusually high, nearing 100 degrees, and remain dangerous to anyone without cooling or hydration, the service said in a brief.

Those with underlying illness, the elderly and children are most susceptible to extreme temperatures and should take extra caution when going outside, the service said.

The service forecasts a slight chance of thunderstorms starting Wednesday night after 11 p.m. and continuing Thursday morning.

Hot conditions are expected to break Thursday with highs in the upper 70s.

Long Island saw widely scattered power outages overnight and into Wednesday morning. By 7 a.m. Wednesday, PSEG Long Island was reporting on its website 35 outages affecting about 400 customers ranging from Garden City to Montauk. 

Tuesday’s temperatures in the lower 100’s were record breaking, as Islip hit 100 degrees around 2:50 p.m. — the first time since July 2011 and first time to reach that temperature in June, Newsday meteorologist Rich Von Ohlen said. It is also the 8th time in history for Islip to hit 100 degrees since records began in 1963.