The weather forecast for Saturday.

The weather forecast for Saturday. Credit: Weather Underground

Saturday will be mostly sunny with highs in the low 70s — a fitting forecast for the first day of fall.

By nightfall, it’ll be mostly cloudy with a low of 56 degrees, the National Weather Service said.

The autumnal equinox is at 9:54 p.m., marking the start of shorter days and cooler temperatures.

There is again a small craft advisory off the South Shore until 2 p.m. Saturday, the weather service said. There is also a moderate to high rip current risk for ocean beaches until the evening, with higher risk for Suffolk County.

Sunday will be partly sunny during the day and a bit cooler with temperatures reaching 70 degrees. Sunday night should bring some clouds and the temperature will drop to the low 50s, the weather service predicts.

Monday will be brisk and bring with it a breeze, the National Weather Service said. Long Island can expect some sun and temperatures to reach a high near 68 for the start of the workweek. Temperatures should dip about 10 degrees Monday night.

Rain is likely to return Tuesday, forecasters said.

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