Long Island weather: Freezing temperatures overnight Monday into Tuesday

A big chill is coming to Long Island, for about nine hours.

Suffolk County will see temperatures dip below freezing overnight Monday into Tuesday, according to the National Weather Service, which issued a freeze warning for the area.

Forecasters have put Nassau County under a freeze watch for the same time period, meaning there's a potential for the mercury to dip below 32 degrees, but it's not certain.

Both alerts take effect as Tuesday begins and they each last until 9 a.m.

"By the early morning hours, temperatures will be around 30 degrees," said John Murray, a meteorologist with the National Weather Service in Upton.

The freeze is "approaching record territory," Murray said.

The last time the temperature went down to 30 on April 21 was in 1965. Normal night temperatures this time of year are in the low 40s.

These cold conditions can harm early spring crops as well as garden plants, the NWS noted.

Experts advise gardeners to protect emerging blooms and delicate seedlings by covering them with burlap bags, sheets or tarps before sundown, to hold the day’s warmth inside, according to The Northern Gardener, a website that specializes in cold-climate gardening.

It recommends gardeners keep heavy fabric off smaller branches or stems with garden stakes or other supports. Potted plants that are not frost-hardy should be brought indoors.

By Tuesday, temperatures will rise to the low to mid-50s, the weather service said.