Christmas, like other winter-solstice holidays, evolved in part as an antidote to the darkest, deadest time of year. What happens, then, when the weather outside’s delightful and the carbon implications of a cozy fire are frightful, when there is no point in putting fresh-baked Christmas cookies out on the fire escape to cool?

Some holiday spirit goes missing along with the snow.

“It messes with your energy,” said Mabrac Matthews, a clothing designer in Flatbush, Brooklyn.

“I haven’t bought a damn thing for anyone,” said Justin Brannan, who runs an art program for children in Bay Ridge, Brooklyn.

This would be an unusually warm December in Jackson, Miss., or Atlanta, or El Paso, on the Mexican border. In New York City, it is shaping up to be the most abnormally warm month ever recorded, by a lot.