Make the most of Thursday’s unusually sunny but cool weather, when the daytime high will be just 77 degrees.
The weather precedes possible rain Friday and then several scorchingly hot and humid days, the National Weather Service in Islip said.
"A prolonged period of heat and humidity is expected Saturday into early next week," the forecasters said.
This prompted the weather service to issue a hazardous weather outlook for that period.
Saturday’s heat indices will hit the lower to mid-90s and then rise to about 100 on Sunday and Monday, the weather service said, adding: "The heat and humidity probably continue into Tuesday with heat indices in the low to mid-90s."
Friday’s scattered storms and thunderstorms — the odds of rain are 50% after midday — also will see temperatures climb back to around 80 degrees, the weather service said.
High temperatures from Saturday to Monday will hover around 90 degrees. Tuesday should top out at 87 degrees and there is a 30% chance of rain Wednesday, when a high of 84 degrees is expected during the day.