A Top 10 Month for Dryness and Warmth
September 2007 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, Cook College/NJAES, Rutgers University
October 2, 2007

Those who thought that this past September was unusual in the atmospheric department were correct. Preliminary calculations (some stations have yet to report) indicate that this was New Jersey's 4th driest and 7th warmest September since statewide summaries were established in 1895.

Rainfall averaged 1.14" across the state, leaving only 1941 (0.27"), 1914 (0.37") and 1895 (1.08") drier (the top 10 list is found below). This is 3.01"below the 1971-2000 average. Rainfall was sparse throughout the state, with only the southeastern, east central and northeast counties averaging over an inch, while western counties and those in the middle and northern coastal regions received between 0.6" and 0.9". Due to the longer-term dry conditions in the southern half of the state, the US Drought Monitor map presently depicts the southernmost counties in "moderate drought: D1" and the counties northward to and including Ocean and Mercer as "abnormally dry: D0." It is interesting to note that this national product does not have a category between these two. On average, October is 0.64" drier than September. Let's hope that is not the case this year!

While not quite as apparent as the dry conditions, September proved to be a warm month. The average statewide temperature of 68.4° tied it with 2002 as the 7th warmest on record and is 3.1° above average. The list below shows that 5 of the 12 warmest NJ Septembers (two ties led to 12 years in the top 10) have occurred in the past 10 years.

September 2005 was warmer and only slightly less dry than this year. October 2005 proved to be the wettest month on record in NJ (11.98"), with temperatures 2.4° above average. That being said, there is no indication of such a moisture turn around this year. Nor can a responsible estimation of precipitation over the upcoming months be made. A La Nina episode is developing in the tropical Pacific, however while past episodes have brought dry conditions to the southeast US and wetness to the Ohio Valley, New Jersey does not show a La Nina preference in precipitation (though the cold half of the year tends to be milder than average).

September in NJ (1895-2007)

Ten Driest "Ten" Warmest
1941 0.27" 1961 71.4°
1914 0.37" 2005 71.0°
1895 1.08" 1931 70.1°
2007 1.14" 1998 68.9°
1948 1.19" 1959 68.8°
2005 1.28" 1945 68.7°
1953 1.44" 2007 68.4° (also 2002)
1939 1.45" 1970 68.3°
1968 1.55" 2004 68.2° (also 1980)
1970 1.60" 1971 68.1°

Past Climate Summaries