December Overview

Precipitation

It was indeed a wet December. Statewide average precipitation (rain and melted snowfall) was 8.10". This is 4.40" above the 1971-2000 average and puts this month in first place as the wettest since 1895. There is a chance that once all station reports are received that this December will drop below 1996; however this year stands no chance of falling to 3rd place (7.29" in 1973).

The heaviest precipitation fell in south Jersey. Vineland (Cumberland County) took top honors with 12.57". The highest totals in other southern counties include 11.56" in Franklin Township (Gloucester), 10.87" at Hammonton (Atlantic) and 10.38" in Woodbine (Cape May). The northwest corner of the state was driest, yet still came in over an inch above average. Mansfield Township (Warren) received 4.75" and Wantage (Sussex) had 5.20".

There were six events where multiple stations received more than 1.00" of rain and/or melted snow. These include (with the top precipitation total listed) the 2nd-3rd with 2.18" in Hamilton Township (Atlantic), the 5th (1.23" Brick Township, Ocean), the 8th-9th (3.17" Woodbine, Cape May), the 13th-14th (1.37" Hamilton Township, Mercer), the 19th-20th (2.44" Buena Vista Township, Atlantic) and 25th-27th (3.46" Little Falls, Passaic). The two major precipitation makers of this group saw all but the northwest corner of the state receive at least 1.50".

Snow

It was a snowy December statewide, with an epic storm smothering most of south Jersey on the 19th-20th. Four storms brought at least 3.0" of the white stuff to multiple locations. The first of these saw an inch or more of snowfall roughly north of Rt. 195 in south-central NJ on the 2nd-3rd. Three communities had as much as 7.0", including Bethlehem Township (Hunterdon), Newton (Sussex) and West Milford (Passaic). The 8th-9th found snow accumulating north of Rt. 78 (north central NJ). Wantage (Sussex) received 7.5" and Jefferson (Morris) had 6.1".

The storm on the 19th-20th dumped a season's worth of snow or more on most areas south of Rt. 195. To the north, totals gradually declined, with the northwest only catching 3-5". With some snow remaining on the ground from previous storms, the first statewide white Christmas since 1995 was assured. During the course of the event, temperatures ranged from the teens in the northwest to the low 30s along the south coast. Some rain and sleet mixed in at times in the latter area, cutting back on snow totals. In open areas, winds gusted in the 30-40 mph range throughout the event, with some higher gusts along the coast. This resulted in considerable blowing and drifting. The following table lists the top snowfall totals in the ten counties where at least 15.0" was measured at one or more stations. A full listing of totals from this storm and others this winter can be accessed here.

Heavy rain and mild temperatures resulted in the loss of most of the state's snow cover during the holiday week. This resulted in moderate flooding of many streams and rivers. However, the last day of the year again mantled all but the extreme southern portion of NJ in white. Totals were mostly in the 1-3" range, with Bethlehem (Hunterdon) at 4.5" and Wantage (Sussex) with 3.7" receiving the most.

Temperature

December's mean temperature of 34.9° was 0.5° below the 1971-2000 mean. However, given the increasing warmth of the past several decades, it ranks close to the median as the 57th warmest (59th coldest) of the past 115 years. The 3rd was the warmest day of the month. Temperatures reached the mid and upper 60s in all but the northwest hills, with stations in four counties reaching 68°. The 9th saw Oswego Lake (Burlington) reach 62°, with a number of stations in southern counties reaching 59° on the 2nd. "Snow eating" temperatures rose into the mid and upper 50s across central and southern areas on the 26th and 27th. The coldest daily maximum of the month was 18° at High Point Monument (Sussex) on the 19th.

Daily minimum temperatures fell into the single digits at one or more location on ten December mornings. Often, these cold readings occur in valley locations when skies are clear, winds are calm and the ground is snow covered. However, when the High Point Monument station is the coldest site one can be assured that winds are howling, with arctic air rushing into the state. The coldest locations on these ten mornings include: 9° at Walpack (Sussex) on the 12th and 13th; 6° and 4° at High Point Monument (Sussex) on the 17th and 18th, respectively; 0° at Upper Deerfield (Cumberland) on the 22nd; -2° and 4° in Berkeley Township (Ocean) on the 23rd and 24th, respectively; 5° at High Point Monument on the 29th; and 8° at Walpack on the 30th.

Yet thus far this winter, a southern station is the only one to fall below 0°. The Berkeley Township station sits at Miller Airpark, an open bowl-shaped low lying area in the Pinelands, where south Jersey's coldest temperatures are often found. This month's lows were the result of a deep, fresh snow cover, and winds calming during the predawn hours at this site and a few others.

Wind

Gusts exceeded 40 mph at one or more NJ observing site on fifteen December days, seven of them with gusts over 50 mph. On several occasions, the strong winds accompanied mild temperatures (3rd, 9th), while at other times they resulted in dangerously low wind chills (17th, 19th-24th, 29th). Days with gusts exceeding 50 mph included the 3rd (58 mph at Hackettstown, Warren); 9th (53 mph at Harvey Cedars, Ocean), 10th (52 mph at Seaside Heights, Ocean); 13th (51 mph at Harvey Cedars); 20th and 21st (56 mph at High Point Monument, Sussex); and 29th (63 mph at High Point Monument; wind chill in the -20° range).

Annual Overview

More often than not, the past several decades have seen New Jersey's annual temperature and precipitation above the century-long average. 2009 was no exception. While not exceptionally warm, the mean temperature of 53.1° was 0.4° above the 1971-2000 average and ranked as the 25th warmest back to 1895. In an anomaly sense, November at +4.5° was the warmest, ranking 4th warmest of the past 115 years. January, at -3.4° was coldest, ranking 25th coldest. August 10th was the warmest day of the year, and January 17th the coldest.

Annual precipitation totaled 54.31", which is 7.11" above average and ranks as the 11th wettest year of the past 115 (see table below). February was the driest month in absolute (0.69") and anomaly (-2.27") senses. December held top wet honors at 8.10" and +4.40". Each of these months was a record setter.

Below is a list of the top weather and climate events during 2009. More information on each event can be found in past climate summaries:

• Dry start to year: Record dry February (0.67" statewide), and driest January through March period on record dating back to 1895.
  
• Late-April heat: Unusually warm weather affects the state from April 25th-28th, with most of the state experiencing high temperatures in the low to mid 90s during this period.
  
• Cool and wet June: 6th wettest June on record (contributing to 5th wettest summer), and 1.7° below normal (25th coolest).
  
• July severe weather: Supercell thunderstorm traverses the north-central part of the state on July 26th, resulting in strong wind gusts exceeding 50 mph, quarter-inch to inch diameter hail in Hunterdon, Somerset, and Union counties, and a lightning-related fatality in Newark. On July 29th, an EF-2 tornado occurs near Wantage in Sussex County, which is the first confirmed tornado in Sussex County since August 1990 and the first F2/EF-2 tornado in NJ since May 2001.
  
• August Hunterdon County flash flood: Heavy rains exceeding 3 inches on August 2nd cause flash flooding in Hunterdon County, particularly in downtown Clinton.
  
• September hybrid storm: Coastal low on September 10th-11th results in three to five inches of rain in southern coastal NJ, and in combination with strong high pressure to the north, produces strong onshore winds and coastal flooding.
  
• October snow: Early-season snow occurs in the northwest portion of the state on October 15th, with higher elevations reporting several inches of accumulation.
  
• Veteran's Day Nor'easter: Slow-moving coastal storm produces persistently strong onshore winds, resulting in major damage to beaches and considerable flooding of some coastal communities.
  
• December snowstorm: An epic snow storm on Dec 19th-20th dropped up to two feet of snow on the southern half of the state.
  
• Record wet December: Wettest December on record, with the largest totals in southern NJ, where monthly reports approached or exceeded a foot in a few locations.

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