How often does New York City stay below freezing (32 degrees) for daytime highs in the winter?

You first have to understand the geography of NYC. It is an island, surrounded by water. So it is a bit warmer than many cities. It also sports a Subway, so the heat generated by the subway keeps the streets a bit warmer too. Sure there are cold days, like any northeast city. But it rarely is below 20 degrees for more than a few days at a time. 

As of this writing, we had 14 inches of snow in 2 days about a week ago. You can barely tell in NYC now, as the heat from the city has melted it away. 

Yes, in the past few years, January temps in NYC can occasionally get has high as 60.  Not often and not for very long, but occasionally. How often does NYC stay below freezing in January?  Seldom for more than 3 or 4 days.  Water freezes at 32, as you know.  But trees don't, animals don't, and people don't.  So there's not much to thaw.  

The islands of HYC (Manhatten, Brooklyn, etc.) are surrounded by wather. That moderates the climate, and makes NYS less likely to experience sub 2o degree temperatures. It depends on the winter. The last one was relatively mild, but there have been cold winters with lots of snow when the temperatures were below freezing most of the time. 

About 80 days per year it does get below freezing.

Too much warm Ocean water to keep it below 32 for two weeks.

http://www.weathergamut.com/2018/01/09/nyc-sub-fre...

2 weeks in a row before a thaw in the 40s?

If you check the link only 5 times in the last century.

Thaw begins at 33.