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A Warm and Wet September: September 2008 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
October 2, 2008

Unlike August, with its dry and cooler than average weather, September was warm and wet across the Garden State. The month saw more afternoons with temperatures exceeding 90° than in August and the first tropical storm crossing New Jersey since Bertha in July 1996 (in 1999 Floyd stayed just offshore). The statewide average temperature of 68.0° was 2.7° above average. This makes this the 13th warmest September since records commenced in 1895 (see table below). Temperatures have been above average in 9 of the past 12 months. September heat was concentrated in the first half of the month, when maxima reached 90° at multiple stations on the 2nd-5th and the 14th. Four south Jersey stations reached 95° on the hottest day, the 4th, with dozens more in the low 90°s. Cooler conditions prevailed later in the month, with morning lows dropping into the mid to upper 30°s from the 19th-21st in northwest valleys and on the 21st in the Pinelands.

Rank Year Avg. Temp.
1 1961 71.4°
2 2005 71.0°
3 1931 70.1°
4 1998 68.9°
5 1959 68.8°
6 1945 68.7°
7 2002 68.4°
8 1970 68.3°
9 2007 68.3°
10 1980 68.2°
11 2004 68.2°
12 1971 68.1°
13 2008 68.0°
14 1921 67.9°
15 1900 67.6°

Rainfall was plentiful in September, with totals exceeding twice the norm in a number of locations. Statewide, an average of 6.30" fell, which is 2.15" above average and ranks as the 11th wettest on record (see table below). Precipitation had been below average during 5 of the previous 6 months. Portions of southern NJ were the driest in September, with the Atlantic County communities of Folsom (3.36") and Hamilton Township (3.69") receiving the least rainfall. Elsewhere, totals exceeded 8" at one or more stations in Bergen, Hunterdon, Middlesex, Monmouth, Morris, Passaic and Somerset counties. South Brunswick (Middlesex, 10.59") and Hillsborough (Somerset, 10.14") received the most rain. The first major event of the month was associated with Tropical Storm Hanna. A leading rain band arrived late on the 5th into the morning of Saturday the 6th, with totals only exceeding 1" at a few coastal locations. The coast was buffeted by wind gusts in the low 40mph range during the PM hours (4 stations had peak gusts of 41 or 42mph). Meanwhile, heavy rain swept into inland areas, tapering off late in the evening. All told, 32 of the 116 Community Collaborative Rain, Hail and Snow network stations reported more than 4", with Morris Township (Morris, 5.57") and Glen Rock (Bergen, 5.46") receiving the most.

Rank Year Prcp. Total
1 1938 9.78"
2 1999 9.58"
3 1934 8.61"
4 1975 8.16"
5 1944 8.14"
6 1907 8.12"
7 1966 7.82"
8 1960 7.73"
9 1989 7.31"
10 1935 6.60"
11 2008 6.30"
12 2003 6.17"
13 1979 6.13"
14 1899 5.91"
15 1996 5.87"

Strong onshore winds with some coastal flooding and beach erosion impacted the state on the 25th-26th, with gusts up to 44mph at Harvey Cedars (Ocean) and 41mph at Sea Girt (Monmouth). These winds were accompanied by some heavy rain, particularly on the 26th, which combined with more downpours on the 28th to finish off the wet month.


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