With the weather running hot and cold this week, meteorologists are warning of the possibility of a severe thunderstorm that could bring damaging wind gusts Wednesday.

The National Weather Service issued a hazardous outlook for Nassau and western Suffolk because an approaching cold front may collide with a mass of unseasonably mild air Wednesday, when the high could hit the mid-60s.

That could bring brief periods of torrential rain and wind gusts of 35 mph Wednesday afternoon and 60 mph at night, meteorologists said. Frequent cloud-to-ground lightning may also be in the works.

But the chance of a severe thunderstorm is a “low probability” for now, said meteorologist David Stark at the service’s Upton office.

He said such storms aren’t unusual as winter transitions into spring and that cool ocean waters off Long Island could tamp down the ferocity of any thunderstorm.

“We’ve been seeing some warmer air masses ahead of some of these cool air masses and when these two combine . . . sometimes you can spark off some strong thunderstorms,” Stark said.

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“It’s just a clash in air masses.”

Once the unseasonably warm air moves on, the cold front could bring a dash of snow Friday, when temperatures dip into the 30s. The service put the chance of snow at 30 percent.

In the immediate forecast, anyone who’s up for a winter day in the mid-50s should stick around for Tuesday.

That’s as the month that was already registering 4.8 degrees above average looks to be ending with another well-above-normal day, temperature-wise. Normal for this time of year is 43 degrees, said meteorologist Faye Barthold, also in the Upton office.

Tuesday is expected to bring mostly cloudy skies, a slight chance of afternoon rain and the potential, too, for afternoon fog, she said. The high is expected to be around 56 degrees.

Rain becomes likely, though, later at night, with patchy fog part of the mix, and temperatures holding fairly steady in the overnight hours in the low 50s, the weather service said.