Never Ending Spring: June 2009 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
July 2, 2009

In many a year, people complain that we "never have a spring anymore", claiming conditions go right from winter to summer weather. Such words certainly were not heard this year, as for the past month those of us in the state climate office have been asked repeatedly when spring will end or if summer will ever arrive. It was a rather dismal June, though not a total washout; more on this below. Looking back, May got off to a wet start, there was a mid-month freeze in some areas, and a lack of any appreciable heat. There were four days of plus 90° F weather in late April, and earlier than that, short-lived 70°+ temperatures arrived within days of the early March snowstorm. Yes, it has been a lengthy spring roller coaster ride!

June clouds were plentiful, statewide precipitation was generous and temperatures were cooler than average. While, at times, this interfered with agriculture, construction, lawn mowing and sport schedules, the good news is that we enter the core of summer without concerns of drought and not having spent much on air conditioning. There were no major weather-related problems in June. Still, there were local impacts from a number of episodes of flash flooding of roadways, rivers and basements, lightning strikes in several cases damaging or destroying structures, and there was the cleanup resulting from the Bergen hail storm (more on this below).

January-March was the driest such interval across the Garden State since records commenced in 1895, thus we needed spring rain. Southern and coastal regions were wettest in April, the central areas in May and the northeast in June. While some flooding occurred as a result of local downpours, no significant river flooding was observed and ground water and river flows rebounded to close to average quantities. So too are the state's reservoirs at average capacities. It took a while for the northwest corner to join in on the rain, but of late, area rainfall has been plentiful.

As June draws to a close, preliminary statewide rainfall totals 6.64", which is 2.85" above the 1971-2000 average of 3.79". This makes this the 6th wettest June since 1895, yet only the 3rd wettest June this decade (see table below). Surprised? Well, 2003 was the wettest June on record (8.61") and 2006 the fifth wettest (7.43"). Of course local conditions vary, with June totals as high as 10.85" in Harrison (Hudson County), 10.36" in River Vale (Bergen) and 10.34" in North Arlington (Hudson). The two driest stations were Bridgeton (Cumberland) with 3.73" and Delran Township (Burlington) with 3.73". Of the almost 100 station reports examined, no other locations received less than 5.00". At least one station received over 9.00" in Bergen, Hudson, Hunterdon, Morris, Passaic and Sussex counties.

Rank Year June Precip
1 2003 8.61"
2 1972 8.41"
3 1938 7.73"
4 1903 7.52"
5 2006 7.43"
6 2009 6.64"
7 1928 6.61"
8 1902 6.43"
9 1975 6.38"
10 1922 6.18"

It was not just the amount of rain, it was how often it fell that made June so damp. Measureable rain (0.01" or more) fell somewhere in NJ on every day of June except the 1st. An inch or more fell at one or more locations on 10 days, and 8 others had between 0.50" and 0.99". Looking at a few stations, Woodbine (Cape May) had rain on 16 days, Sicklerville (Camden) on 20 days, Hillsborough (Somerset) on 22 days and Haworth (Bergen) on 20 days.

The clouds helped to keep June temperatures on the cool side. The preliminary statewide average temperature of 67.7° is 1.7° below average. This ranks June 2009 as the 25th coolest of the past 115 years. No doubt many believed the cool conditions to be more pronounced. This is likely for one of two reasons. First, the frequent clouds and moist surface conditions resulted in daytime highs that were 3-4° below average. However, they also resulted in nighttime lows that were quite close to average, as the lower atmosphere is slow to lose its daytime heat when night skies are not clear. Taking New Brunswick as an example, the mean high for the month was 3.4° below average while the nighttime low was 0.5° above average.

The second reason for the perception of coolness requires turning to the media (particularly the New York metro sources) and their reliance on strictly urban stations for reports of anomalies during the course of the month. In fact, Newark (-3.1°) and Central Park (-3.7°) had larger anomalies than suburban and rural reaches. Why was the urban area anomalously cooler? Another two part explanation follows. Part one centers on changes of station conditions. Newark's thermometer was moved to a cooler location on the airport grounds in the mid 1990s. Thus readings since then are a degree or two cooler than they would be had the station not moved. The anomalies reported for June 2009 and other months are calculated from 1971-2000 means, thus any recent monthly mean since the move is going to be 1-2° cooler against the long-term mean than it would have been had the station not moved. At Central Park, considerable foliage has been permitted to grow surrounding the recording station, thus it appears (a more definitive study is in the offing) that this station is cooling relative to its past conditions (thus from its 1971-2000 mean) due to the effects of the additional foliage.

Another possible contributor to the cooler urban anomalies this past June has to do with the urban heat island. Typically, urban daytime heating is retained into the night, resulting in daytime highs a little warmer than outside the urban area, and in particular elevating nighttime lows compared to other locations. This is due to buildings and paved areas that absorbed heat during the day retaining their warmth far longer into the night than fields and forests. This past June, the clouds and rain reduced the daytime heating of these heat absorbing surfaces. Therefore come night there was not as much heat retained and thus more of an opportunity for more cooling (despite clouds). Thus, for instance, the daily high for June at Newark was 3.9° below average (only a 0.5° cooler anomaly than at New Brunswick, where the station sits outside the center of town at Rutgers Gardens) and the low 2.1° below average (2.6° cooler than the New Brunswick anomaly). This issue is ripe for further study, but I thought that those of you who regularly read these monthly reports might find this of some interest.

Blame the less-than-ideal weather of this past month on the delayed seasonal retreat of the jet stream into Canada. This resulted in the frequent passage of waves of low pressure through the Mid Atlantic states. This stubborn pattern resulted in frequent cloudy, rainy days or partly sunny days with frontal passages accompanied by showers and thunderstorms during the first two weeks of the month. A stalled low pressure system off the coast in the third week contributed cool, showery conditions. During the last week of June, more seasonable conditions began to emerge, with warmth, humidity and occasional showers interspersed with sunny skies.

Examining June observations further, the first morning of the month was by far the coldest. Walpack (Sussex) had a rather unusual low at the freezing point. Elsewhere, lows between 36-39° were observed at several stations in Hunterdon, Ocean, Passaic, Somerset and Warren counties. A thunderstorm brought 0.59" of rain and a 45 mph wind gust to the Atlantic City Marina (Atlantic) on the 2nd. The first of a number of wet episodes (where one or more locations received over 1.50" of rain) occurred on the 3rd-4th, with Mendham (Morris) receiving 1.90" and Woodbine (Cape May) 1.89". A gust of 49 mph hit Upper Deerfield (Cumberland) in a storm on the 3rd. June 5th proved to be an unusual June day statewide. Nearly continuous rain fell from the predawn hours into the night, something more often seen during the winter. As much as 2.08" fell in Little Egg Harbor Township (Ocean) and the clouds and rain kept daytime highs from a maximum of 63° in West Cape May (Cape May) to a minimum of 55° at High Point (Sussex).

A cluster of thunderstorms moved through north Jersey in the predawn hours of the 9th, and a rush hour squall line drenched the entire state later that morning. The double shot of rain brought 2.44" to Parsippany (Morris) and 2.28" to Kearny (Hudson). The strongest recorded gust that day was 40 mph at Clayton (Gloucester). The northwest was soaked on the 11th-12th with 1.83" at Wantage. The next two days saw 2.14" fall in west central NJ at Stockton (Hunterdon). A thunderstorm traveled slowly through a portion of Bergen County on the afternoon of the 15th. Along with 1.51" of rain at Haworth and 1.45" in River Vale, a prodigious amount of pea to marble size hail fell in a swath through portions of the Township of Washington, Westwood and Emerson. Front end loaders were called out to clear roadways where hail had washed into foot plus mounds, snow blowers were dusted off and hailmen were assembled! It was the amount of hail, rather than the size of the hail stones that made for one of NJ's more epic hail events.

A local thunderstorm produced a 41 mph gust to Mullica (Atlantic) on the 15th. Another episode of steady, heavy rain occurred on the 18th. This brought 2.78" to Paramus (Bergen) and 2.56" to Harrison. The shore location of Belmar (Monmouth) was drenched with 1.69" on the 21st, with a thunderstorm dropping 1.58" at Lavallette (Ocean) on the 26th. A storm on the 26th produced a 68 mph gust at High Point Monument (Sussex). The thunderstorms of the 26th were generated on one of the two warmest days of the month. Highs reached 89° at several observing sites in Atlantic, Camden, Cape May, Salem and Somerset counties. This same mark was reached again at locations in Atlantic, Camden, Gloucester, Passaic and Somerset counties on the 30th. Could it be that summer has arrived to stay for a few months?

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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