Long Island weather: Dry and sunny with temps in the low 70s on last weekend of summer

A man sits on the dock at the Theodore Roservelt Park in Oyster Bay as the sun goes down. Sept 20, 2025 Credit: Neil Miller
Warm weather is expected on the last weekend of summer on Long Island, with sunshine and temperatures around 70 degrees through early next week, according to National Weather Service meteorologist Brian Ciemnecki.
Saturday will be dry and sunny with a high in the low 70s. Ciemnecki said those conditions would continue on Sunday and Monday, when temperatures would be in the high 60s to low 70s.
"Really nice, really pleasant conditions," Ciemnecki said about the forecast. "It’s going to be a beautiful weekend."
Monday is the autumnal equinox, the official start of fall in the Northern Hemisphere. But Long Islanders shouldn’t expect it to start feeling like autumn for a while yet, according to Ciemnecki.
He said the cooler temperatures likely won’t take hold until "sometime in October."
This weekend’s temperatures are in-line with what’s typical at this time of year, Ciemnecki said.
"Today, seasonal or normal in Islip would be a high of 74. We’re going to be right around normal today," he said. "And then we’ll be a couple degrees below normal tomorrow. So, we’re right where we should be for this time of year."
Rainfall on Long Island continues to be under where it should be, however. Ciemnecki said the region was "slightly below normal for the month, "about 7 1/2 inches short of what’s typical at this point in the year.
Long Island usually gets about 45 inches of rain per year, according to the U.S. Geological Survey, meaning the region would be about 17% short if the current deficit persists through the end of 2025.
"We are abnormally dry, but we’re not hitting severe drought levels," Ciemnecki said. "Overall, we could use some rain."
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