Plenty of Flowers (and Pollen): May 2009 & Spring 2009 Wrap Up

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
June 5, 2009

May Overview

Near average temperatures and precipitation in May made for rapidly growing lawns and blossoming plants. Statewide, the preliminary monthly temperature was 61.3°. This was the 42nd warmest May of the past 115 years (tied with 1969), coming in 0.8° above average. Monthly precipitation across the state averaged 4.38". This was 0.08" above average, but due to the skewness of monthly rainfall to the low side it was the 36th wettest, not as close to the center point (57th or 58th place) as one might expect. The largest May totals included 6.54" in Hillsborough Township (Somerset County) and 6.41" in Holland Township (Hunterdon). Wall Township (Monmouth) at 2.81" received the least, followed by Bridgeton (Cumberland) with 2.99".

Measureable rain fell each of the first seven days. Top honors went to Hillsborough with a cumulative 4.67" and South Brunswick (Middlesex) with 4.47". Even the "driest" areas received a soaking; witness Bridgeton (Cumberland) with 1.94" and Wantage (Sussex) with 1.90". Over that period, there were multiple events that dumped over an inch at one location or another. This includes a series of thunderstorms on the 6th and 7th that brought 2.30" to Randolph Township (Morris). Two CoCoRaHS stations situated about 3 miles apart in Mendham Township (Morris) received 2.27" and 2.28". South Brunswick and Hillsborough Township received 1/4" (pea-sized) hail on the 7th.

Thunderstorms on the 14th brought as much as 1.09" to Winslow Township (Camden) and 1.05" to Mantua Township (Gloucester). Two days later, thunderstorms dropped 1.76" on Blairstown (Warren) and 1.32" on Andover (Sussex). The 24th-25th brought some thunder and 1.33" to Andover and 1.04" to Hillsborough. The last event of the month had maximum totals of 1.33" in Hammonton (Atlantic) and 0.99" in New Brunswick (Middlesex).

Unlike April, with four days of maximum temperatures exceeding 90°, none occurred in May. There were four days with maximums in the mid to upper 80s, from the 20th-22nd and on the 24th. Haworth, at 88°, took top honors on the 22nd. Other locations that reached 85° or 86° on one of these days included Hillsborough Township, Howell (Monmouth), New Brunswick and Toms River (Ocean).

Two May mornings saw temperatures dip below freezing at one or more low-elevation locations. Walpack (Sussex) dipped to 30° on the 13th, when Pequest's (Warren) low was 33°. A more unusual freeze occurred on the 19th, when Pequest fell to 28° and Walpack to 29°. Other counties with minimums from 30° to 32° on the 19th included Hunterdon, Passaic, Somerset, Sussex and Ocean. This freeze was 3-4 weeks later than the average last freeze at these locations.

As spring progresses and pressure gradients diminish, it is typical to find fewer windy days. This year was no exception, as April had 11 days with gusts exceeding 40 mph at one or more stations, something that occurred on only three days in May. A 51 mph gust was observed at High Point (Sussex) on the 10th, a 44 mph gust at Mullica (Atlantic) on the 14th, and a peak gust of 53 mph occurred at Wantage (Sussex) on the 17th. Peak gusts of 39 mph were noted at High Point on the 2nd and 9th and at Harvey Cedars and Seaside Heights (both in Ocean County) on the 26th.

New Jersey only had a few dangerous weather-related misfortunes in May. Minor flooding, particularly on the Millstone River in Somerset County, occurred during the first week. Lightning shocked four individuals hiking on the Appalachian Trail near the Delaware Water Gap in Warren County on the 24th. One of these individuals was hospitalized with non-life threatening injuries and the other three were treated and released. There were no reports of agricultural damage resulting from the freeze and frost on the 19th. With little home heating or air conditioning required, May utility bills will likely bring a smile to many a customer.

Spring 2009 Overview

The March-May interval had temperatures averaging 51.6°, or 0.9° above average. This places spring 2009 in the upper quartile as the 23rd warmest. Of the three months, April was the most above normal, followed by May and then a close to average March. The thermal highlight of the spring was the four-day heat wave in late April. Second place goes to the wide swing in temperatures over a four-day period following the early March snowstorm (from -2° to 79° at Woodbine in Cape May County). Third were the freezing temperatures at scattered locations around the state on May 19.

Precipitation totaled 11.16" over the three months; ranking spring 2009 as the 53rd wettest at 1.24" below average. The most notable event of the season was the snowstorm that kicked things off on March 1-2. Totals exceeded 10" in portions of coastal NJ and a few locations in the south and in the northern Highlands. Six events in April had rainfall exceed 1.00" at one or more locations. The first week of May brought over 6.00" to west-central NJ.

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
NJ Snow Event Reports

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Past Climate Summaries