Temperatures colder than 10° above zero are infrequent in New York. A typical winter averages three such days (in the 21st century the average has fallen to two days per winter.) Not surprisingly, two-thirds of NYC's frigid readings have occurred in January. The sweet spot is between Jan. 16-22, with the peak day being January 18, which has had readings in the single digits nine times. Since 1970 the earliest date for a single-digit reading has been Dec. 3, which occurred in 1976; the latest was on February 28, 2014.
Temperatures of zero or below have been reported just eleven times since 1970, with the coldest reading of 2° below zero occurring on three occasions: Jan. 17, 1977; Jan. 21, 1985; and Jan. 19, 1994. There has been just one sub-zero reading this century and it occurred during the mild winter of 2016, when the mercury dropped to -1° on Valentine's Day. Not only was it a record for the date, it was also the first below zero reading since 1994, the first to occur in February since 1963 and the latest sub-zero reading since 1934. (Previous to 2016's reading, the coldest reading of the 20th century was +1°, which occurred twice in January 2004.)
The winters of 2015, 1979 and 1994 have had the most days with single-digit readings, nine, followed by the winters of 1977, 2004 and 2005, which had eight. The most consecutive winters to have a sub-zero reading is four, 1933 to 1936. And the most consecutive days with single digit temperatures is six, which happened between Feb. 9-14, 1979. By contrast, 13 winters have had no readings below 10 degrees, including six of the past ten (through the winter of 2017).
Just one day since 1970 has had a high temperature in the single digits. It occurred during the great Arctic outbreak of January 1985. On Jan. 21 the high reached only 9° (after an AM low of -2°). That reading was reached shortly before midnight. During the daytime hours the temperature hovered around 7°. This was the coldest high temperature for New York since Feb. 15, 1943 when the high that day was just 8° (and that was the second time that winter with a high of 8°; the first was on Dec. 20).
Finally, in this century New York's first three most extended Arctic outbreaks occurred in consecutive years - January 2003, 2004 and 2005. The fourth occurred in February 2015. These outbreaks all averaged more than 10 degrees colder than average.