It was a wet year, indeed, ranking as the fourth wettest on record (behind 1983*, 2011 and 1972). However, it began on the dry side, with January receiving just 2.18" of precipitation (it was the third drier than average month in a row, with just 5.97" measured in total; and five of the six years preceding 2018 had below average rainfall). And while the amount of precipitation that fell during the first half of the year was close to average, the rain gauge worked overtime in the second half as 40 inches was measured, 56% greater than what fell in the first half (five of the six months had six inches or more of precipitation). And although the year wasn't the wettest on record, it did claim the crown for most days of measurable precipitation. As 2018 came to a close it seemed fitting that it ended with a soaking rain on New Year's Eve, making it the wettest 12/31 since 1948, and the first time since 1994 that rain fell as the ball dropped in Times Square.
* An argument can be made for 2018 being ranked third because 1983's claim as New York's wettest year has been called into question after it was revealed that the rain gauge in Central Park was broken for a large part of the year, allowing rain to enter from multiple.
Now let's shine some light on the year's other major weather stories:
- The year began with the continuation of a two-week cold wave that started the day after Christmas 2017 and lasted thru 1/8, making it the second longest on record (average high/low for its entirety was 23/13). During this cold wave the biggest snowstorm of the winter snarled the City with nearly ten inches of wind-blown snow on 1/4.
- February was the mildest on record (pushing Feb. 2017 to second place) and featured a temperature of 78° on 2/21 (35 degrees above average); this was the warmest reading ever posted in the first two months of the year.
- March was cold (at 2.4 degrees below average it was colder than our mild February) and stormy, with four nor'easters wreaking havoc. The last one, which occurred the day after the spring equinox, dropped 8.4" of snow, the biggest March snowfall since 1993 (and 0.1" more than the snowfall of March 1-2, 2009).
- Cold spring weather continued into April (3.6 degrees below average), which saw the biggest April snowfall since 1982. 5.5" fell the morning of Easter Monday (4/2), forcing the Yankees to postpone their home opener. 2018 suffered through the coldest March/April since 1984. (However, among all years it ranks 56th as springtimes before 1950 were significantly chillier.)
- May was a reversal of March-April and was the sixth mildest on record. The month began on the hot side, with highs in the 90s on the 2nd and 3rd; later in the month there were three days with highs in the upper 80s.
- A severe, quick-moving thunderstorm during evening rush hour on 5/15 caused extensive disruptions (including my flight to JFK which was cancelled). Then six months later a surprise snowfall during the afternoon and evening was even more debilitating, snarling the evening commute for hours.
- Despite May's warm conditions, Mother's Day was chilly and overcast, with a high/low of 54/52. By contrast Father's Day was sunny and hot, with a high/low of 91/66.
- The year's rainiest period was a six-week stretch in July and August (7/12-8/22) when 15.77" fell (nearly ten inches above average for the period). This included a deluge of 2.24" in little more than an hour on 7/17. However, the year's biggest rainstorm occurred in April when 3.29" fell on 4/15-16.
- The latest dates for a 80-degree and 70-degree low were reported on 8/29 and 10/10, respectively. The year had 55 days with lows of 70° or warmer, the fourth most on record (following 1906, 2005 and 2015, and tied with 2010).
- A surprise snowstorm on 11/15 (6.4") was followed a week later by a frigid Thanksgiving Day (high/low of 28/17). This resulted in the coldest temperatures ever encountered during the the Macy's Thanksgiving Day parade - and the following morning was even colder, with a low of 15°. After this early taste of winter there wouldn't be another measurable snowfall or colder temperatures for the rest of the year.
- Like the majority of years this century 2018 ranked among the 25 warmest years on record, ranking 18th. However, it wasn't as warm as the previous three years (2017 ranked 14th, 2016 ranked sixth and 2015 placed ninth).
- Finally, 2018's diurnal variation between its average high and low was the smallest in more than 100 years (2003's and 1996's were close behind, 0.1 degree wider). Interestingly, there are 15 years with smaller variations, all which occurred between 1878 and 1910. (Many thanks to Eugene Demarco for sharing his analysis with me.)