A Split Precipitation Picture: September 2009 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
October 6, 2009

Following a wet summer statewide, September saw a continued abundance of moisture in southern New Jersey, while the north was rather dry. Statewide, precipitation averaged 4.45". This is 0.30" above average and the 36th wettest September of the past 115 years. From Mercer, Middlesex and Monmouth counties south, the September average was 5.00", making this the 29th wettest September. To the north, the 2.44" average resulted in the 31st driest September since 1895.

Cape May County took honors as the wettest location, with three stations in Woodbine reporting from 7.35" to 7.78" for the month. Sea Isle City received 7.60", and Upper, Middle and Lower Townships were soaked with 7.59", 7.42" and 7.39", respectively. Estell Manor in nearby Atlantic County received 7.67". On the low end of the ledger, two stations in Wantage (Sussex County) reported 1.58" and 1.84", while Andover (Sussex) at 1.75" and Somerville with 1.86" also came in under 2".

The first six days of the month were dry statewide. Wall (Monmouth) received 1.82" from a local storm on the 9th. The first major widespread event occurred from the 10th-11th when a coastal low pressure system impacted the southern half of NJ. Rain totaled 4.82" in Woodbine, 4.79" in Dennis Township (Cape May) and 4.50" in Sea Isle City. Sixteen south Jersey Community Collaborative Rain, Hail and Snow (CoCoRaHS) network stations received more than 3", with 94 southern stations reporting over an inch of rain. Accompanying the rain were strong coastal winds which gusted to 61 mph at the Atlantic City Marina (Atlantic), 57 mph at Seaside Heights (Ocean), 56 mph at Harvey Cedars (Ocean) and 50 mph at Sea Girt (Monmouth) on the 11th. While the low pressure system was not deep, NJ was wedged between this low and high pressure to the north, thus partially accounting for the strong onshore winds and resultant coastal flooding.

The 12th-13th, 16th and 24th saw scattered storms across the state. Westfield (Union) took top honors during the first event with 1.70". Howell (Monmouth) saw 1.48" on the 16th and Burlington (Burlington) 1.36" on the 24th. The 26th-27th brought the most widespread rainfall event of the month to NJ. Again, the south took top honors, with 2.15" at Ocean City (Cape May) and 2.14" at Egg Harbor (Atlantic). All the state received at least a half inch, with 84 of 148 CoCoRaHS stations receiving at least an inch.

The September statewide average temperature of 65.1° was 0.2° below average. This is the 57th coolest or 59th warmest on record! Maximum temperatures failed to exceed the 90° mark anywhere during the month. The warmest day was the 5th, when three south Jersey stations reached 87° (Hammonton (Atlantic), Cherry Hill (Camden) and Oswego Lake (Burlington)). The 4th, 13th, 23rd and 24th all saw one or more stations in the southern half of the state reach 85°. A number of stations throughout the state were in the low 80s on those occasions.

Minimum temperatures at the usual cool valley locations in northwest Jersey fell into the low 40s on the 1st and 2nd. Pequest (Warren) reached 41° on the 2nd. The fall season's first low in the 30s occurred at Pequest on the 19th (37°). This was followed by 35° at Walpack (Sussex) on the 20th. Walpack also took low honors with lows between 35° and 39° on the 25th, 26th, 29th, and 30th. The 26th saw lows in the state widely range between 35° at Walpack and 64° at West Creek (Ocean). Even coastal areas dropped to the mid 50s on the last day of the month, which was the coolest statewide.

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

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