Monthly Summaries

With 565 incorporated communities in New Jersey, one would think that the odds of multiple significant weather events specific to any one of them within a month would be exceedingly rare. Yet July 2019 brought such a duel scenario to not one but two NJ townships. Mt. Laurel (Burlington County) was visited by two tornadoes, while one rain gauge in Stafford Township (Ocean) caught 5.00” in two separate 24 hour periods. More specifics are provided later in this report. The good news is that, despite damage occurring in each of the four events, there were no fatalities nor reported injuries.

The month as a whole was a wet one, averaging 6.15” across the state. This is 1.58” above the 1981–2010 mean and ranks as the 20th wettest since 1895. Northern counties were wettest, averaging 7.20” or some 2.45” above normal and ranking 16th wettest. The south averaged 5.61”, which is 1.12” above normal and ranks 29th wettest.

Ten of the past 12 months and 15 of the past 18 months have received above-average precipitation across the state. While the 12 months ending in January this year ranks as wettest (66.61”) of 1484 such intervals dating back to 1895, the past 12 month period ending in July comes in second place with 65.74”, just ahead of the 12 months ending in June (65.50”).

Much like last month, March 2019 had a wide variety of weather conditions across the Garden State. The month came in like a lion, with a week of wintry weather, which was particularly snowy in northern and central regions. More snow fell than in any other month this season and the temperature fell below zero in one location and down to single digits at a number of others. The remainder of the month was often lamb-like, including four days with high temperatures exceeding 70° at many locations and six in the 60°s. Several inch-plus rain events occurred, along with the first lightning-filled squall line of the year, which, in some locations, included hail and strong winds.

The statewide monthly temperature averaged 39.7°. This is 1.1° below the 1981–2010 average and is the 58th mildest (66th coolest) since 1895. The statewide average rain and melted snow totaled 3.91”. This is 0.20” below the 1981–2010 average. It was the 61st wettest (65th driest) March since 1895.

Statewide snowfall averaged 6.3”. This was 1.9” above average. Northern counties averaged 13.0” (6.7” above average), the central region 8.6” (+3.5”), and south 1.6” (-1.5”). As a preview of the seasonal snow summary in next month’s report, statewide snowfall through March is 20.5”, 5.0” below average. Barring the unlikely case of April snowfall exceeding any other month of the season, this will mark the first time since records began in 1895 that March was NJ’s snowiest month of the season for three consecutive snow seasons (October–April).

If there was one thing the weather of January did not possess, it was a consistent identity. Though one might say that conditions during the first month of 2019 were consistently inconsistent, oftentimes with rapid transitions. Yet when all was said and done, conditions did not average too much from the long term norm. Statewide, the average temperature of 31.9° was just 1.2° above the 1981–2010 mean and ranks as the 35th mildest since 1895. This included two days where the thermometer topped 60° in a few locations and four days with some places falling below zero. Rain and melted snow totaled 4.39” on average, which was 0.99” above average. This ranks as the 28th wettest January on record. Four events brought more than an inch of liquid to some locations, yet there was a two-week stretch without such an abundant total.

Snowfall averaged 3.8”, which is 3.4” below normal and ranked as the 44th least snowy January dating back to 1895. There was one somewhat notable snow event in the south and two in the northwest, though there were no “blockbuster” winter storms. Central and northeastern areas were almost shut out for the month in the snow department, and for that matter, mostly devoid of snow since the unseasonable event of November 15. For instance, Newark (Essex County) received just 0.9” and New Brunswick (Middlesex) 0.8”, the least in January for each station since 2008. For the month, snowfall over the north division averaged 5.8” (-3.5”), central 1.8” (-6.1”), and south 3.8” (-2.0”). For the season thus far, NJ has averaged 8.9” (-3.9”), the north division 13.7” (-3.5”), central 6.6” (-7.7”), and south 7.5” (-2.5”).

For the fourth consecutive year, summer weather stubbornly hung on well into September across the Garden State. The statewide average temperature of 70.4° was 4.6° above the 1981–2010 mean, and ranks as the third warmest since records commenced in 1895. September 2017, now ranking 11th, sat in the top 10 for just one year before being bumped out by 2018. This September was the fifth consecutive month of above-average temperatures. The past 12 months have seen the 2nd warmest October, 4th warmest May, 1st warmest August (tied with 2016 based on updated figures), and now the 3rd warmest September. The June through September period this year averaged 73.3° (+2.5°), making it the 4th warmest on record. The top 10 such intervals have all occurred since 2005. The August–September average of 73.7° (+4.3°) was the warmest on record, followed by 2005, 2016, 2015, and 2010.

Perhaps what was most interesting about temperatures this past month was the disparity between average maximum and minimum temperature anomalies. The average maximum of 77.7° was 1.4° above average and ranked 27th warmest. However, the average minimum of 63.2° was 7.9° above average and is a whopping 2.2° milder than the previous highest September average minimum. This came about due to the excessive cloud cover and humidity throughout most of the month, which kept the days from getting too warm and, come nighttime, “trapped” much of the heat gained during the day within the lower atmosphere. Thus, unlike the past three warm Septembers (as well as 2013 and 2014), each of which had below-average precipitation, this year was anything but dry. There were frequent rainy episodes, which at times produced localized deluges and resultant flash flooding. The statewide average rainfall of 7.60” is 3.55” above the 1981–2010 average, and is tied with 1960 as the sixth wettest September since 1895. The wettest September on record remains 1999, which averaged 9.50 inches, in no small part due to Tropical Storm Floyd’s rains. Aside from 1999, you have to go back to 1975 to find a September with more rain than this year.

July 2018 had a classic variety of summer weather. There was: 1) an ongoing heatwave to begin the month; 2) dry conditions for the most part in the first half of the month; 3) some warm, exceedingly humid conditions with widespread, at times heavy, showers the second half of the month (courtesy of the subtropics); and 4) some “top 10” sunny dry days following several cold front passages (thank you Canada).

The average statewide July temperature was 76.4°. This is 1.8° above the 1981–2010 average and ranks as the 13th warmest July in 124 years of records (2.6° above the full period of record average). Eleven of the 18 warmest Julys since 1895 have occurred in the past 20 years (since 1999). The average daily maximum temperature across the state was 87.2°, which is 2.2° above average and ranks as the 15th warmest on record. The 65.6° average minimum was 1.4° above the 1981–2010 average and comes in as the 17th warmest.

Statewide, August precipitation averaged 5.63”. This was 1.53” above the 1981–2010 average and ranked as the 32nd wettest since 1895. It was the wettest August since the record wettest month in 2011. As is often seen in the summer, the majority of the precipitation fell in scattered showers and thunderstorms. This resulted in a wide range of monthly totals around the state, with some serious flash flooding occurring in several locations when moisture ladened storms parked themselves over an area for multiple hours. Where storms missed time and time again, rainfall totals were below average. The northern NJ climate division (Hunterdon, Somerset, and Union counties northward) saw their 10th wettest August on record, with an average of 8.28” falling. This is 4.17” above average. Since 1990, only August 2011 was wetter in this division.