The National Weather Service has issued a freeze warning for 10 New Jersey counties, including Monmouth, Mercer, Salem, Gloucester, Camden, Burlington, and Cape May. The warning is in response to sub-freezing temperatures expected between 25 and 30 degrees, which could potentially kill crops, other sensitive vegetation, and potentially damage unprotected outdoor plumbing. The warnings are usually issued from May to October, when low temperatures are expected to fall.