Today in New York Weather History: December 17
Dec. 17 is the average date of the first high temperature of 32° or colder (based on the period 1970-2020). It's happened as early as Nov. 22 (in 2008) and Nov. 23 (1989), and as late as Jan. 20 (1986). In more than half of the years the first high of 32° or colder was 31° or 32°, but it's been as cold as 20° (which happened in the winter of 2007-08, when it occurred late, on Jan 3).
A snowfall of six inches (three inches this evening, three inches tomorrow morning) came four days after a snowfall of seven inches.
Four days after the temperature reached 61°, tonight, shortly before midnight, the mercury dropped to one degree above zero. This was the first of fifteen days this winter with lows in the single digits or colder.
Snow that began late in the morning continued through early morning on 12/18. amounting to 7.2". It was also a very cold day, with a high/low of only 21°/10°. (The snow was gone by Christmas Day, which had a high of 59°.) The next measurable snowfall wouldn't be for another seven weeks (2/4).
Today's frigid high/low of 20°/8° (22 degrees below average) would be the coldest day of the winter. Skies were clear.
This was the twelfth day in a row with above average temperatures. During these dozen days temperatures were ten degrees above average. Even after passage of a cold front early this morning, and temperatures falling throughout the day, the mean temperature was five degrees above the norm. This stretch of mild weather followed a two-week period of colder than average weather.
The epic ice storm that began yesterday afternoon continued through this morning. Conditions were worse than yesterday as sleet and freezing rain fell at an even heavier rate. In total, 1.46" of precipitation fell - all in the form of sleet or freezing rain. The temperature stayed below freezing all day, and by midnight had fallen to 17°.
Light showers through early afternoon amounted to 0.12". This was the 146th day this year with measurable precipitation, establishing 1996 as the year with the most days of precipitation in the 20th century, passing 1972, the previous crown holder. And there would be six additional days of precipitation before the year ended. (The average number days of precipitation per year is 121.)
Today was the 25th day in a row with above-average temperatures. During this stretch of mild days temperatures were ten degrees above normal. (This would be the mildest December since 1984.)
Today's high of 62° was a record for the date, just one of five days with above-average temperatures during a December that was quite cold (5.5 degrees below average) - the coldest since 1989.
This was the 18th day in a row in which no low temperature was duplicated. During these days (beginning on Nov. 30) they ranged between 32° and 58° - all above average.
Only three degrees separated the day's high (43°) and low (40°) on a raw, "gloomy Gus" kind of day.
Light snow, occasionally mixed with sleet, fell throughout the daytime hours and amounted to 1.5". This was the fourth snowfall of the past ten days, totaling 8.6". Three of these snow "events" delivered one-inch+ - the most such snowfalls in December since 2005. Besides being snowy, the ten days since 12/8 were also quite cold, with the average high/low of 35°/26° nearly eight degrees below the norm.
It was a mild and rainy day. The 1.25" of rain that was measured in Central Park fell mostly between 11 AM and 4 PM. This was the eighth day in a row that had a mean temperature more than 10° degrees above average. The average high/low during these days was 63°/52° - nineteen degrees above average.
Six days after the first measurable snow of the winter (0.4"), today saw the first snowfall of one inch or more as 2.8" accumulated between 4-8 AM. Then it changed to sleet, then to freezing rain, all of which was over by noon. (By contrast, last winter's first one-inch snowfall wasn't until 1/23 - the blizzard that buried the City under its biggest snowfall on record.)
Light wraparound showers in the wee hours of the morning (amounting to just 0.03"), remnants from yesterday's rainstorm, made this the 152nd day this year with measurable precipitation, tying 1996 for the all-time record. What distinguishes 2018 from 1996 is that its total precipitation for the year was more than five inches above 1996's (with two weeks remaining in 2018).
Just three days after Central Park registered its lowest humidity level in December this century (20% later in the afternoon), today had an even lower humidity level - 14% (also during late afternoon). As low as this was, it was twice as high as the 7% humidity reported on 4/6 of this year.