A Rare Cold Month
In a Year of Extremes
December and Annual 2010 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
January 3, 2011

December Overview

The last month of 2010 reminded us that temperatures can fall below average and snow can fly across the Garden State. Not that residents will soon forget this past snowy February, however the bulk of the year featured well above average temperatures and an extend period of drought. More on the year is found later in this narrative, however first a look at December.

Cold temperatures prevailed throughout most of the month, with approximately 80% of the days averaging below the long-term mean. The statewide monthly average of 30.7° was 4.7° below average. This tied with 1943 as the 22nd coldest December since records commenced in 1895.

The warmest day was the 1st when Hammonton (Atlantic County), Bethel Mill Park (Gloucester) and Cherry Hill (Camden) topped out at 66°. Most other locations in NJ were in the low 60°s. The 11th-13th was the only other time when some locations exceeded the 50° mark, with West Cape May at 50° on the 11th, the three warmest stations on the 1st also leading the way with 60° on the 12th, and Woodbine (Cumberland) and Toms River (Ocean) reaching 50° on the 13th.

A powerful cold front caused temperatures to quickly plummet, with the warmest locations in south Jersey only reaching 27° on the 14th while High Point Monument (Sussex) maxed out at 14°. All of NJ remained below freezing on the 15th and 16th. On eleven days in December temperatures bottomed out in the single digits in at least one location. The 9th saw Berkeley Township (Ocean) at 7°, and both Pequest (Warren) and High Point (Sussex) at 9°. These stations fell to 6°, 7°, and 8°, respectively, on the 10th, with 8° also observed at Basking Ridge (Somerset). High Point Monument dipped to 8° or 9° on the 13th, 14th and 15th. Pequest took low honors from the 17th-20th, with lows from 6° to 9°. Hope (Warren) fell to 9° on the 17th and Berkeley Township reached 9° on the 18th.

With a deep fresh snow cover and a calm atmosphere, Berkeley Township fell to 9° late in the evening on the 29th, dropping further to 0° on the morning of the 30th. The 30th was the coldest morning of the month statewide, with single digit lows observed in eight counties, and the warmest low of 24° found at the Atlantic City Marina (Atlantic).

Three storms impacted New Jersey during December, depositing the vast majority of the month's precipitation. The statewide average of rain and melted snow was 3.31". At 0.39" below normal, this ranks as the 60th wettest or 56th driest December on record. The most precipitation fell in the north central Highlands, with 7.40" at West Milford (Passaic), 5.89" in Mine Hill Township (Morris), 5.71" in Hardyston Township (Sussex) and 5.57" at Jefferson Township (Morris). In the northwest corner of the state, the least amount fell, with 2.52" and 2.77" observed at two locations in Wantage (Sussex) and 2.93" at Washington (Warren). The southwest area came in on the lower side too, with 2.88" in Upper Deerfield (Cumberland).

The 1st brought the wettest system of the month to NJ. Totals (some of which included minor amounts that fell on November 30th) included 3.70" and 3.01" at two West Milford (Passaic) locations and 3.08" in Mine Hill Township (Morris). 1.00-3.00" fell in all but the far southern portions of the state, where 0.75"-1.00" was measured. A second storm beginning late on the 11th and ending early on the 13th brought a similar pattern of precipitation, with the far south and portions of the southwest receiving 0.75"-1.00" and the remainder of the state from 1.00" to just over 2.00". Top totals included 2.29" at Little Falls (Passaic), 2.22" and 2.18" at the West Milford stations, and 2.14" and 2.09" at two Oakland (Bergen) locations.

Snow squalls dusted portions of central NJ on the 6th and 15th, only amounting to a maximum of 0.3" in Greenwich Township (Warren) on the 6th and 0.5" at Bethlehem Township (Hunterdon) on the 15th. These totals paled in comparison to what fell in just minutes during the major blizzard that impacted the state from the morning of the 26th into the early morning of the 27th. A combination of heavy snowfall and strong winds crippled the eastern half of the state. Some locations received from 24.0"-31.0", ranking amongst the top several heaviest snowfalls on record. Meanwhile, a sharp precipitation gradient saw some western portions only receiving single digit totals of wind-driven flakes.

It was a difficult snowfall to measure and equally difficult to extract a liquid total by melting a core of snow taken from an area with a depth representative of the snow that fell. This was the only manner in which a reasonably accurate total could be obtained. Those observers who did so found approximately a 14:1 ratio of snowfall to liquid. Using what many consider a traditional 10:1 ratio gave too high a precipitation total. Meanwhile, those attempting to catch and melt snowfall in a mounted gauge caught far less snow in the gauge than actually fell, due to the wind and, of course in many areas, the gauge overfilling with snow.

An impressive 213 snowfall reports were submitted by volunteer observers from the NJ CoCoRaHS, National Weather Service spotter networks, and NWS Cooperative and first order stations and were deemed reasonable ("accurate" is a difficult word to use when measuring blizzard totals) by the state climate office. Of these, totals ranged from a low of 2.7" in Belvidere Bridge (Warren) to 32.0" at Rahway (Union). The table below shows the range of totals received from stations in each NJ county. Variations within counties down the center of the state are impressive, due to the sharp cut off of the heaviest snow bands across this region. Totals to the west and east differ in part due to banding, but also illustrate some of the difficulties in coming up with a representative snow depth for the windy storm.

County Minimum Maximum
Atlantic 11.2 20.1
Bergen 15.5 23.0
Burlington 8.5 19.2
Camden 8.8 12.0
Cape May 10.5 22.0
Cumberland 7.0 11.5
Essex 21.1 24.8
Gloucester 8.2 13.5
Hudson 19.9 26.0
Hunterdon 3.5 7.3
Mercer 4.9 16.0
Middlesex 19.5 28.0
Monmouth 20.0 31.0
Morris 6.0 18.5
Ocean 16.5 30.0
Passaic 17.0 25.5
Salem 1 report 4.8
Somerset 7.0 19.5
Sussex 4.0 9.8
Union 25.0 32.0
Warren 2.7 7.0

Table 1. Minimum and Maximum snowfall totals at observing sites in the 21 NJ counties. See a complete listing of snowfall reports here.

The highest atmospheric pressure of the month was approximately 30.45" on the 10th, while the second storm of the month saw pressures across NJ drop to 29.10"-29.15" on the 13th. Pressures during the blizzard fell to 29.15"-29.20" on the 27th.

With three major storms and lots of cold air pouring in from the Arctic, wind was a major factor throughout December. On 17 days, at least one location received a gust exceeding 40 mph, while on nine of these days gusts topped 50 mph. The storm on the 1st saw winds gust to 54 mph at Wantage (Sussex) and Bivalve (Cumberland). The 6th-8th was a gusty period at High Point Monument and nearby Wantage, with gusts of 53 mph and 51 mph, respectively, on the 6th and gusts in the 40s mph the other two days. The mid-month storm brought gusty winds from the 12th-15th, first with a 46 mph gust at Bivalve and then Wantage and High Point Monument dominating the scene. This included gusts to 58 mph and 54 mph, respectively, on the 13th, and a 53 mph gust at Wantage on the 14th. These two perennially windy locations saw another interval of persistent gusts from the 20th-24th, including three days with gusts between 51 mph and 58 mph.

The blizzard brought a gust to 55 mph at High Point Monument on the 26th, however even when the snow stopped falling, ground blizzard conditions prevailed at times on the 27th, the windiest day of the month. Gusts that day reached 58 mph at Seaside Heights (Ocean), 57 mph at High Point Monument, 55 mph in Harvey Cedars (Ocean), and 50 mph at Sea Girt (Monmouth), while topping 40 mph at a number of other locations. Fittingly, High Point Monument had the last 40 mph gust of the month on the 28th, topping out at 46 mph.

Winds associated with the storm on the 1st toppled trees and utility poles throughout the state. A motorist was killed by a falling tree in West Milford (Passaic) and 18,000 utility customers lost power. The wind and rain also led to major airport and rail delays.

The blizzard was the most impactful event of the month and resulted in a state of emergency being declared by the acting governor. Transportation by road, rail and air was brought to a halt, especially over eastern portions of the state. This included hundreds if not thousands of vehicles stranded on local, state and interstate roads, leading to rescue operations and the opening of several shelters. It took several days to bring the transportation system back to full operation, especially in hard-hit Monmouth and Ocean counties. There were scattered power outages over the course of the storm. Several lives were lost (the number yet to be fully determined) as a result of prolonged exposure to the elements, automobile accidents and snow shoveling.

Annual 2010 Overview

Mother Nature pulled no punches when it came to the extreme weather/climate conditions that impacted the Garden State throughout 2010. Before presenting the state climate office's top ten events of the past year, an examination of annual temperature and precipitation is in order.

We entered December tied with 1998 for the warmest first eleven months of the year on record. However the cold conditions experienced during the last month of the year dropped 2010 into a tie for the third warmest year on record (Table 2). Note that eight of the warmest ten years have occurred since 1990.

Rank Year Avg Temp
1 1998 55.6°
2 2006 55.3°
3 2010 54.8°
4 1949 54.8°
5 2002 54.8°
6 1990 54.7°
7 1991 54.6°
8 1999 54.4°
9 1953 54.2°
10 2008 54.1°

Table 2. Warmest years in New Jersey since statewide records commenced in 1895 (116 years).

The wet start to the year combined with a dry spring and summer resulted in a statewide annual precipitation total of 45.59". This is only 1.61" below average, and ranks as the 52nd wettest of the past 116 years.

Top ten lists are always subject to debate, be it due to those items included OR excluded, along with the order of the ranking. We would love to hear your comments on the list that follows (or feel free to agree!) at Remember, we were looking for events with widespread impacts. You may have experienced a severe storm at some point that was mainly localized, leaving a memory for you, but perhaps not many others. Also, when considering statewide records, they extend back to 1895.

1. March 12th-14th storm: rain, flooding, wind (part of a record wet March)
2. Snowiest February (record snowiest winter in southern half of state)
3. Every month from March through September ranked in the top ten for warmth (3rd warmest year)
4. December 26th-27th blizzard
5. Dry April through September with an end of summer statewide Drought Watch

The next five are mostly associated with one of the top five events:
6. Back-to-back February 5-6 and 9-10 snow storms
7. Driest summer since 1966 (8th driest overall)
8. July 4-7 heat wave (record number of maximum temperatures greater than or equal to 90° for the season at some locations)
9. Beneficial "drought busting" rainfall (August 22nd and September 30th - October 1st), though in some locations too excessive
10. Absence of a major cold wave (a mid-December outbreak came closest to achieving such a designation)

For those seeking more detailed information on hourly, daily and monthly conditions, please visit the following Office of the NJ State Climatologist's websites:

NJ Weather and Climate Network
NJ Community Collaborative Rain, Hail and Snow Network
NJ Snow Event Reports

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Past Climate Summaries