Don’t turn ‘Blue,’ wear a warm hat

YOU KNOW it’s cold outside when the NYPD orders a uniform change.

As scores of police officers prepare to tackle 10-degree temperatures as they guard Times Square this New Year’s Eve, the department is allowing rank-and-file officers to wear knit hats instead of their traditional headgear.

“A winter knit hat is now authorized as an optional uniform item for all uniformed members of the service,” a department memo read. The memo was sent to all precincts on Thursday, in advance of the New Year’s Eve chill.

But there’s a small hitch — a thick hat with a pom-pom isn’t going to cut it.

“The approved optional winter knit hat must be navy blue in color with ‘NYPD’ embroidered on the front in white one inch block lettering,” the memo read.