The autumn of 2015 brought exceptionally warm conditions to New York City. According to the NWS Central Park climatological station, it tied 1931 for the all time warmest meteorological Fall (September, October, November) on record.
Overall, the city’s average temperature for the past three months was 61.8°F. That is 4.2°F above average. Looking back, every month of the season was above its long-term norm. In fact, September and November each broke their monthly temperature records.
While winter is coming and overall temperatures are dropping, they are warmer than average for this time of year. The main reasons for this are likely a combination of global warming and a strong El Niño, which tends to push the jet stream further north than normal. Weather records for Central Park date back to 1869.