Summer

While it is exceedingly rare to see monthly or seasonal temperature departures from normal differ in sign or even notable magnitude between southern and northern portions of New Jersey, such is not always the case for precipitation. This August and summer as a whole exemplify such disparities. While rain was often plentiful in the north, more often than not, the south did not see gauges fill as much or as often. This report will first address August conditions in the Garden State, finishing with a recap of climatological summer (June–August).

August precipitation averaged 6.52” across NJ. This is 1.95” above the 1991–2020 normal and ranks as the 22nd wettest August since records commenced in 1895. The northern climate division (Hunterdon-Somerset-Union and all counties to their north) averaged 8.53”. This is 3.97” above normal and ranks as the 10th wettest. The southern division (Mercer-Middlesex-Monmouth and all but immediate coastal areas to the south) came in at 5.39”. This is 0.82” above normal and ranks 41st wettest of the past 130 Augusts. The coastal division averaged 4.37”, which is 0.23” below normal and ranks 60th wettest (71st driest).

Despite wide-ranging weekly differences, statewide August temperatures were just 0.3° above normal, averaging 73.9°. This ranks as the 30th warmest back to 1895, certainly not near a ranking close to the mid-point of the entire period of record, thus exemplifying how much NJ has warmed over recent decades. The north averaged 72.2° (+0.3°, 28th warmest), the south 75.0° (+0.4°, 30th warmest), and the coast 75.0° (+0.3°, 25th warmest).

Above-average temperatures ruled in June. So, what else is new? As will be seen later in this report, the first half of 2024 ranked as the second warmest since statewide records commenced in 1895. June 2024 was also the 7th consecutive month with temperatures above the 1991–2020 average and 10th of the last 12 in that category. June itself came in as New Jersey’s 2nd warmest, tied with 1943 and just behind 2010. Six of the 11 warmest have occurred since 2005. The 73.6° average was 3.3° above normal. The average high of 85.1° was 4.1° above normal, tied for the 2nd warmest, and the average low of 62.0° was 2.4° above normal, ranking 4th warmest. Each of the three NOAA state climate divisions had their 2nd warmest June. The north averaged 71.7° (+3.1°), south 74.8° (+3.4°), and coast 73.8° (+3.3°).

As often occurs during the warm season, the rainfall pattern was a mixed bag as the month progressed and also across the state on any given day. Overall, the state experienced a dry month, with the majority of the state considered Abnormally Dry (D0) in the last US Drought Monitor assessment of the month. With some rain falling after the June 30th approximate 7–8 AM observing time of most National Weather Service Cooperative and Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS) stations, any daytime or evening rain is entered into the record book as falling on July 1st. Thus, the official map below does not include some of the heavy post-observing time heavy rain in Cape May County the morning of the 30th nor rain occurring elsewhere in the state later in the day. For the month, the state average 2.74”, which is 1.56” below normal and ranks 28th driest. The north averaged 2.23” (-2.38”, 13th driest), south 3.07” (-1.07”, 49th driest), and coast 2.84” (-1.01”, 51st driest).

Yet another warmer-than-normal July is in the books. Nine of New Jersey’s 11 hottest Julys dating back to 1895 have occurred since 2010. Unlike last year where the heat was accompanied by the 12th driest July, this year was a wet and humid one, the 22nd wettest on record. The statewide average temperature of 77.2° was 1.8° above the 1991–2020 normal and 3.3° above the 1895–2021 period-of-record mean, ranking 10th warmest on record (tied with 2016). The average high was 87.0°, 1.3° above normal and ranking 18th warmest. The average low was 67.4°, 2.3° above normal and ranking 4th warmest. The northern climate division averaged 75.2° (+1.5°, 12th warmest), the southern division 78.5° (+2.0°, 10th), and the coast 78.3° (+2.1, 8th).

The 6.27” statewide average precipitation was 1.56” above normal to earn the 22nd wettest ranking. The northern division averaged 7.37” (+2.65”, 16th wettest), southern division 5.64” (+0.90”, 30th), and the coast 5.09” (+0.71”, 36th). The largest totals were found in Warren County and adjacent northwest counties, with some totals over a foot. The Pinelands region received the least, with totals of 2.50” to 3.50”.

When it comes to recent hot Julys in New Jersey, the beat goes on. This year the heat was joined by quite limited precipitation, something not often seen in recent years. The statewide average temperature of 78.1° was 2.7° above the 1991–2020 normal, ranking 6th warmest since records commenced in 1895. Eight of the ten warmest Julys have occurred since 2010, leaving only 1955 and 1999 as top-ten outliers. The statewide average maximum was 88.6° (+2.9°, 6th warmest) and the minimum 67.5° (+2.4°, 4th warmest). Northern counties averaged 75.9° (+2.2°, 9th warmest), southern counties 79.5° (+3.0°, 3rd warmest), and coastal areas 78.8° (+2.6°, tied as 4th warmest).

Statewide July precipitation averaged 2.19”, which is 2.52” below normal, ranking as the 13th driest on record. Of the top 15, only two have occurred this century. The north averaged 2.03” (-2.69”, 14th driest), south 2.30” (-2.44”, 14th driest), and coast 2.16” (-2.22”, 17th driest). The central portion of the state was driest, with less than 2.00” accumulating, and under an inch in the driest areas. Closer-to-normal totals were found in the northwest, northeast, and southwest. At month’s end, portions of central NJ were classified as being in moderate drought (D1) on the weekly U.S. Drought Monitor map. This denotes conditions not seen more than once every five to ten years. Surrounding central and northern areas were considered abnormally dry (D0), as was the southeast corner of the state. This all coincides quite well with the most pronounced precipitation deficits of the past month.

Whether the thermometer was reading high or low this August or whether rain was falling or not, one factor that most always had to be considered was the high level of humidity. The “Dog Days” of summer indeed. Of course, there was much else to consider this month, including contributions of rain from two tropical storms, one of which brought the largest crests on some rivers since May 1, 2014, 11 days where one or more locations received at least 2.00” of rain, and 16 days where the high temperature reached 90° or higher somewhere in the state.

Adding up all the rainfall, the statewide monthly average was 6.87”. This is 2.30” above the 1991–2020 normal and ranks as the 15th wettest August since 1895. The northern climate division led the way with 7.89” (+3.33”, 11th wettest), followed by the coastal area with 6.65” (+2.05”, 21st wettest), and the southern division at 6.21” (+1.64”, 27th wettest).

The statewide average temperature of 75.9° is 2.3° degrees above normal and ranks 4th warmest. Seven of the top 10 and 13 of the warmest 20 have occurred this century. The warmth was most strongly a function of elevated nighttime temperatures, which, for NJ, averaged 66.9°. This is 3.6° above normal and ranks 2nd warmest. The maximum temperature averaged 84.9°, some 1.1° above normal and ranks 18th warmest.