It's looking a lot like 1879 out there. On this date in 1879 the high temperature in Central Park was 64 degrees. It hasn't gotten that warm on this date since then. A quick look at the monthly weather almanacs indicates that that is the sixth oldest daily high record still on the books. The oldest for any day being set in January 1874. This afternoon's high is going to come pretty close to breaking that ancient record but we're probably going to fall a degree or two shy.
Tomorrow is likely to be warmer, reaching the mid-60s, but the record of 68 degrees set in 1931 is probably safe. Sunday's record is in peril, however. The coolest forecast of 64 degrees, from the National Weather Service, would tie the 1923 record. Other forecasts are going a couple of degrees warmer than that. The abnormally warm weather concludes on Monday when the high is expected to reach the lower 60s.
Monday's warm weather looks to be wet, warm weather as a drenching rain is likely to precede a cold front that should pass late that night. There's not exactly any cold weather behind the front as Tuesday through Thursday could still reach the upper 50s, which is only fifteen degrees warmer than normal for mid-December.