Long Island weather: Melting mounds could cause flooding, black ice; snow possible Monday

The historic blizzard that wreaked havoc across Long Island this week now gives way to the threat of snow melting, then freezing, and then melting again, forecasters said.

The National Weather Service said overnight temperatures have led to black ice conditions, creating hazards for drivers Thursday. It also warned that rising daytime temperatures between now and Saturday could lead to ponding water in susceptible low-lying areas across the Island.

The wide range of temperatures, predicted to be in the high 30s daytime Thursday and Friday and as high as 46 degrees on Saturday, followed by subfreezing conditions each overnight, will create travel turmoil.

The warming-freezing-warming cycle is creating potholes on roads and ponding conditions in many prone areas during the warming cycle. That could lead to icing and black ice road conditions when that water refreezes.

Weather service meteorologist Matthew Wunsch said this storm brought snowfall packed with "a lot of moisture, high water content," which made this snow, and how it melts and refreezes, very different from the earlier snowstorm this winter.

But the weather service believes flooding will only be an issue if we see dramatic rainfall before that snow melts completely, and no major rainstorms are predicted in coming days. Some areas of Nassau and Suffolk could see light rain Thursday afternoon and evening.

There is also a chance Long Island will see more snowfall Monday into Tuesday, though the weather service currently predicts that likelihood at about 30%.

Check back for updates on this developing story.

By John Valenti

john.valenti@newsday.com

John Valenti, a Newsday reporter since 1981, has been honored nationally by the Associated Press, Society of the Silurians and National Headliner Awards for investigative, enterprise and breaking news reporting, as well as column writing. He is the author of “Swee'pea,” about New York playground basketball star Lloyd Daniels. His debut crime novel, “For Nothing Is Hidden,” rooted in 1950s Long Island, was released in October 2025.