A cold air mass from Canada is heading for Maine, which will send temperatures plummeting Thursday night into Friday morning. The National Weather Service projects temperatures to fall to 5 or 10 degrees below zero in southern Maine, while the wind chill could make it feel as cold as 30 below zero. Hunter Tubbs, a meteorologist at the agency’s Gray office, said the cold will be most severe inland. Closer to the coast, “low temperatures will probably be in the single digits, either side of zero,” Tubbs said. If the brunt of the storm does curl into the Atlantic Ocean as expected, Maine will still feel its lingering presence offshore.