Fall Freeze

Last month’s report spoke of how “classic” the weather was during October. November’s weather could be classified as being anything but such. The month began with perhaps the warmest first ten days of November on record in the Garden State, an interval that ranked up there with early November 2020. Then came winter-like temperatures for about ten days leading up to Thanksgiving before the month ended on a closer-to-normal note. There were only two mid-month events that brought more than an inch of rain to parts of the state, one associated with the remnants of a late-season hurricane that struck Florida. Portions of central and northern NJ saw the first snowflakes of the season during the cold spell, though aside from some minor accumulations at higher elevations, mostly traces were observed.

With the ups and downs of temperature, November came out averaging 47.5° for the state as a whole. This is 2.4° above the 1991–2020 normal and ties as the 15th mildest eleventh month on record. Ten of the twenty mildest Novembers since 1895 have occurred since 2001. The statewide average high temperature of 58.1° was 3.4° above normal, ranking 10th mildest. The average low of 36.9° was 1.4° above normal, ranking 20th mildest. North Jersey averaged 45.2° (+2.1, 15th mildest), south Jersey 48.7° (+2.4°, 17th mildest), and the Jersey coast 50.0° (+2.7°, 13th mildest).

Statewide precipitation averaged 3.08”, which is 0.28” below normal and ranks as the 63rd driest (66th wettest) on record. The north averaged 2.98” (-0.28”, 63rd driest), south 3.14” (-0.15”, 71st driest), and coast 3.14” (-0.20”, 68th driest). As the monthly map shows, central and northern coastal areas were wettest, while the driest areas were scattered in the far south, central, and north. It must be noted that the rain falling during the second half of the 30th is not included in the monthly totals for the state, regions, or individual stations presented later in the report. By convention, the reporting day for most National Weather Service (NWS) Cooperative and Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS) stations used in this report ends at morning observation time on the last day of the month. Totals from the afternoon of the 30th, to be included in December totals, ranged as high as about an inch, though mainly 0.25”–1.00”.

November was the first month since May 2020 with both averages of precipitation and temperature below 1991–2020 normals. The last drier-than-normal month was this past June while the last cooler-than-normal month was this past May. However, it’s been a while, 19 months, since the two anomalies teamed up. And dry it was, with the statewide average of 1.06” running 2.29” below normal. This ranks as the 7th driest November since records commenced in 1895. Only two other Novembers since 1936 fall in the top 10.

The statewide average November temperature of 43.9° was 1.2° below the 1991–2020 normal and ranked as the 73rd coolest of the past 127 years. This was 17.2° cooler than the mild average of this past October. The normal difference between the months is 10.2°. The average maximum was 54.5° (-0.2°, 84th coolest) and the average minimum was 33.2° (-2.3°, 47th coolest). The north averaged 41.9° (-1.2°, 74th coolest), the south 44.9° (-1.4°, 68th coolest), and the coast 46.0° (-1.3°, 70th coolest). The first Rutgers NJWxNet or NWS Cooperative station to reach the freezing point this season was Pequest (Warren County), late on the 2nd. This was the latest first freeze in NJ since at least 1900 (based on Coop records). The last location to reach freezing was West Cape May (Cape May) on the 28th, on the late side but not unusually so.

September 2020 was a month of widely-varying temperatures, several episodes of heavy precipitation, and an extended dry spell. Put it all together and conditions averaged quite close to normal. The statewide monthly average temperature of 66.8° was 1.0° above the 1981–2010 mean. While it was the seventh month of 2020 to average above normal, it was the first of these not to rank in the top 10 for warmth. Rather, it ranked 33rd warmest of the past 126 Septembers. Divisional departures from normal ranged from +0.7° in the north to +1.5° along the coast. The statewide average maximum temperature was 76.6°, which is 0.3° above normal and ranks 47th warmest. The average minimum of 56.9° was 1.6° on the warm side and ranked 24th mildest. High temperatures were likely reduced by several degrees during a mid-month period when a veil of smoke from western US forest fires blanketed the sky at an altitude of about 15,000 feet when skies otherwise would have been blue, especially on the 15th–16th. It is uncertain if this kept minimum temperatures somewhat warmer than they would otherwise have been. A cold front moved through from the northwest on the 18th, clearing the skies and sending temperatures plummeting. What followed was a four-day spell of temperatures that were well below average, including four nights with below-freezing temperatures at three to four Rutgers NJ Weather Network sites. While freezes resulting from cold air draining into valleys in some northern locations are not unprecedented before the end of astronomical summer, it is highly unusual for the cold to persist over four consecutive nights.

As the 10th month of 2019 commenced, attention was on the continuing flash drought conditions across the Garden State. Lawns had gone brown and shallow rooted trees were losing their dull-colored leaves early. By the second week of the month, the US Drought Monitor showed all of NJ to be in either abnormally dry (D0) or moderate drought (D1) status (full disclosure: my recommendations are taken under consideration by the national author of each week’s map). Several rain episodes in the first half of the month, particularly in the north, began to stall any worsening of conditions. However, it wasn’t until the last half that five events deposited an inch or more, three of them with two inches or more, at a number of locations around the state. Thus by month’s end, only portions of southwest, southeast, and central NJ were rated D0, and the remainder, as we like to say, in “D nada.” This turn to storminess didn’t come without consequences. This included localized flash and small stream flooding on occasion, several episodes of strong winds, and some minor to moderate coastal flooding. More on all of this below, but first to further summarize the month. In the precipitation department, the statewide average was 5.79”. This is 1.90” above the 1981–2010 normal and ranks as the 15th wettest dating back to 1895. North Jersey came in with an average of 6.72”, some 2.41” above normal and ranking 10th wettest. In the south, the 5.28” average was 1.65” above normal and ranks as the 20th wettest.

As if the wet month was not newsworthy enough, the statewide monthly temperature of 58.0° tied with two other years as the 9th warmest back to 1895. This is 3.5° above normal, with northern and southern portions coming in at 3.2° and 3.8° above, respectively. The 2nd was arguably the hottest October day on record, thus also the warmest for so late in the season. Meanwhile, several locations experienced the first freeze of the season on the 4th or 5th, with a more widespread frost and freeze on the 19th. Still, the month ended with only 18 of the 63 NJWxNet stations having fallen to the freezing mark.

With today’s (11/12) minimum temperature at West Cape May (Cape May County) and Lower Alloways Creek Township (Salem) falling to 30° and 32°, respectively, the growing season has ended across the Garden State. The growing season is considered to be the count of days between the last freeze of the spring and the first freeze of the fall (counting neither of those freezing days). This made for a 214 day growing season at West Cape May, while the Lower Alloways Creek Township weather station was just installed in July, thus a seasonal number is unavailable. These first freezes were preceded by a day at the Atlantic City Mariana (Atlantic) and Harvey Cedars (Ocean), which fell to 32° and 31°, respectively, on the 11th. Based on observations from these Rutgers NJ Weather Network stations (the 62 stations upon which the growing season is determined), these two locations had NJ’s longest growing seasons. The Marina saw its last spring freeze on March 22nd, giving it a 233 day season. Harvey Cedars last froze on April 2nd, thus ended with a 222 day season.