Sunday is forecast to start off chilly in the low to mid-30s with mostly cloudy skies all day, the National Weather Service said.
There's no chance of rain Sunday but there's a small chance of rain Monday and Tuesday, said David Stark, a weather service meteorologist.
"The forecast from Sunday through Tuesday is mostly cloudy, all three days, with a chance of rain Monday and Tuesday at any time, but it's not going to be a washout," he said. "We're just going to be in a setup where that chance of rain is not zero."
Temperatures will be in the mid-40s on Sunday, near 50 on Monday and mid-40s again on Tuesday, Stark said.
"After Tuesday there's no chance of precipitation through Thanksgiving," though "we are going to be getting much colder Wednesday and especially on Thanksgiving," he said.
Wednesday's temperatures are expected to be in low 40s.
"On Thanksgiving we're going to struggle to get above the freezing mark with temperatures to start the day maybe in the low to mid-20s and we're forecasting high temperatures on Thanksgiving between 32 and 34 degrees right now," Stark said.
The high Saturday in Islip was 50.
The normal high in Islip this time of year is in the low to mid-50s, with lows in the upper 30s.