The unseasonably mild fall weather that began in the middle of September persisted throughout October, resulting in a month that was 7.2 degrees warmer than average. With an average high/low of 71/57 this was the warmest October on record, finishing ahead of 2007 and 1947 by 0.5 degree. 14 days were 10+ degrees above average; 19 had highs of 70° or warmer - second only to October 1947's 22; and just three had chillier than average readings. Until the end of the month it appeared October would also be characterized by a lack of rain as less than an inch fell in the first four weeks. However, that storyline ended on 10/29-30 when a nor'easter drenched the City with 3.28" of rain - more rain than the previous 60 days. This was New York's biggest rainstorm in three-and-a-half years (since 4/30/14 when 4.97" fell). Other highlights:
- The record for the latest date with a low in the 70s was established and then re-established on consecutive days (10/8 and 10/9). Interestingly, despite these tropical readings, neither day had a high in the 80s.
- The month's chilliest mean temperature occurred on 10/17, with a high/low of 58/42 (six degrees below average). The chilliest high, 57°, occurred on Halloween. Only two other days had lows below 60°. The month had a dozen days with lows of 60° or warmer, tying Oct. 2007 for the most in the years since 1900.
- The three days with below average mean temperatures were widely separated - on 10/1 (three degrees below average), 10/17 (-6 degrees) and 10/31 (-2 degrees).
- The warmest stretch of the month was a seven-day period, 10/5-11, which was 14 degrees warmer than average. Each day had a high of 77° or warmer and all seven days were 10+ degrees above average. The average high/low of this week was 80/67, comparable to late August.
- Although it reigns as the mildest October on record, eleven other Octobers had more days with highs of 80°+ (this year's had four). The warm days of these eleven months were balanced by cold periods that this October didn't experience. Speaking of which, this October tied October 1984 and 1949 for the fewest days with lows below 50° - just five.
- For the first time since 1990 October was milder than May. Typically, May is five degrees warmer but this year it was three degrees cooler.
- Finally, October joined four other months that, since the beginning of 2015, became the warmest on record: Feb. 2017, Dec. 2015, Nov. 2015 and Sept. 2015. And five other months became the second or third warmest. (An outlier was Feb. 2015, which was the third coldest on record.)