Record-breaking high temperatures on Sunday will segue into a chilly start to the week on Monday, forecasters said.

Temperatures on Sunday reached a high of 60 degrees in Islip, breaking the record of 58 degrees, said Faye Barthold, a meteorologist with the National Weather Service in Upton.

Rain Sunday night could put a damper on the heat spike and make way for cooler, more typically December-like temperatures Monday, with temperatures in the 40s.

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“It’s going to be much cooler and back to seasonable, with temperatures in the low 40s — which is going to feel like quite a shock,” said Carlie Buccola, a meteorologist with the National Weather Service.

What’s more, a mix of rain and sleet will follow the dip and lead to all rain by Tuesday afternoon. The day’s high will be 52 degrees before the rain clouds make way for partly sunny skies Wednesday.

The midweek day’s high will be 52 degrees, the low 44 degrees, Buccola said, adding that rain may accompany the mild temperatures into the evening hours of Wednesday and wee hours of New Year’s Eve.

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Thursday should bring clouds with temperatures varying widely from a high of 53 to a low of 36 — still unseasonably high, Buccola said. New Year’s Eve temperatures rarely exceed readings in the 20s, she said.

Friday, New Year’s Day, will be partly sunny with a high of 45 degrees, turning to partly cloudy skies and a low of 32 degrees for the night.

The dry weather and temperatures in the low to mid-40s continue into Saturday, Barthold said.

@Newsday

With Christine Chung