Unless Long Islanders are traveling by sleigh, drivers should be careful on the roads Saturday night as meteorologists predict patchy black ice for Suffolk County.

Saturday morning’s rain and temperatures dipping below freezing will combine to create the conditions for black ice, which causes roads to become slick, said meteorologist Nelson Vaz with the National Weather Service in Upton.

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Saturday night also will bring patches of fog to Long Island.

On Sunday — Christmas Day and the second day of Hanukkah — conditions will be mostly sunny and dry, Vaz said.

High temperatures will be in the low to mid-40s, which is “a tad above normal for this time of year,” he said.