Yet Another Hot Month:
July 2011 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
August 2, 2011

The first two days of July were quite sunny, with seasonably warm daytime and comfortable nighttime temperatures and low humidity levels. There were other such "top ten" days in the month too, for instance the 9th, 10th, 15th, 16th and 27th. Most other days were, shall we say, more "challenging", with bouts of extreme heat, an extended period of dry weather, and some occasions with drenching, dangerous thunderstorms. When all was said and done, New Jersey experienced its second warmest July (any month for that matter) on record (back to 1895). The average temperature statewide was 78.8°, which is 3.8° above the 1981-2010 normal. This is only 0.2° away from the record warm July of 1955 and surpasses 2010, which falls to 3rd place (Table 1). Notice that six of the ten warmest Julys of the past 117 years have occurred in the past eighteen years.

Rank Year July Temp.
1 1955 79.0°
2 2011 78.8°
3 2010 78.6°
4 1999 78.4°
5 1949 77.8°
6 2006 77.3°
7 1994 77.1°
8 1901 77.0°
9 1993 76.9°
10 1952 76.8°

Table 1. The ten warmest Julys across New Jersey since 1895.

Continuing on with some additional impressive numbers, when averaged together, June and July 2011 rank second in warmth, only ranking behind the same period last year. The same can be said of the April-July and May-July averages. Ten of the past seventeen months have ranked in the top ten for warmth, with only December 2010 and January 2011 having below-average temperatures during this period. Notice that 1981-2010 normals are being used for the first time. The new July normal temperature is 0.5° warmer than the previous normal, testament to the warm Julys in the past decade, warmer than those in the 1970s.

July precipitation averaged 3.98" around the state, which is 0.54" below the new normal and 0.51" below the old normal. This ranks as the 52nd driest July since 1895. Much as in June, there was a wide range of rainfall totals across NJ. Interestingly, the driest area in June, Burlington County, was one of the wettest in July, while the situation was reversed in northeast NJ. Tabernacle (Burlington County) received 8.16" at one station and 7.15" at another. Woodland (Burlington) had 7.66", Wantage (Sussex) 7.54", and Woodbine (Cape May) 7.52". On the dry side, Glen Rock (Bergen) only saw 1.95", Harrison (Hudson) 1.96", Saddle Brook (Bergen) 2.09", and 2.82" and Tenafly (Bergen) 2.16".

Before looking into the storms of the month, we will look further at temperatures. Maximum temperatures reached 90° or higher on 26 July days at one or more of the approximately 50 stations monitored. The highest temperature in the state stayed between 86° and 89° on the 1st, 3rd, 14th, 25th and 27th. On eleven days the maximum equaled or exceeded 95°. The 7th saw Cherry Hill (Camden) reach 96°, with Hawthorne (Passaic) at that mark on the 12th and Jersey City (Hudson) there on the 18th. Sicklerville got to 97° on the 19th.

Torrid heat baked NJ from the 21st to 23rd. The first day saw Hillsborough (Somerset), Haworth (Bergen), and Hawthorne reach 100°. Only the coast saw temperatures below 90°, with the Atlantic City Marina (Atlantic) coolest at 80°. The 22nd will go down as one of the five or ten hottest NJ days since widespread records began in the 1890s. The century mark was equaled or exceeded in every one of NJ's 21 counties, a very rare occurrence indeed! (See Table 2) The 108° at Newark Airport was the highest observed there since the station originated in 1931. This is only 2° below the all-time state record at Runyon (Middlesex) on July 10, 1936. New Brunswick's (Middlesex) 105° was 1 degree below their all-time record on August 7, 1918 (July 6, 2010 and several other dates also saw 105°). Of the stations monitored, 34 reached the century mark. At 92°, Bivalve (Cumberland), next to Delaware Bay, had the lowest maximum. All minimums on the 22nd were at least 72°, with Newark only down to 86° and several non-urban stations at 81°.

County Location Max. Temp.
Atlantic Atlantic City AP (Pomona) 105°
Bergen Teterboro AP 104°
Burlington Oswego Lake & Mansfield 102°
Camden Somerdale 104°
Cape May Cape May 102°
Cumberland Seabrook Farms 102°
Essex Newark Airport 108°
Gloucester Piney Hollow & Bethel Mill Park 101°
Hudson Harrison 107°
Hunterdon Flemington 103°
Mercer Trenton 106°
Middlesex New Brunswick 105°
Monmouth Freehold-Marlboro 104°
Morris Chatham Township 104°
Ocean Berkeley Township & West Creek 102°
Passaic Hawthorne 103°
Salem Carneys Point 104°
Somerset Hillsborough 104°
Sussex Andover 101°
Union Berkeley Heights 104°
Warren Pequest 101°

Table 2. Maximum temperature New Jersey's 21 counties on the afternoon of July 22, 2011.

The heat continued on 23rd, with Atlantic City Airport leading the way at 105°, Somerdale (Camden) second warmest at 103°, and Atlantic City Marina surprisingly coming in as third warmest at 102° (tied with Estell Manor (Atlantic), Cape May, and Newark Airport). Nine stations reached 101° and thirteen got to 100°. Again, no station maxed out below 90°. The morning low was again 86° at Newark Airport, 84° at Atlantic City Airport, 83° at Harrison, and 82° at three other stations. The atmosphere never made it above 100° the remainder of the month, however Atlantic City Airport reached 100° and Sicklerville (Camden) reached 98° on the 24th, and South Harrison (Gloucester) made it to 96° on the 29th, 95° on the 30th, and 96° on the 31st.

Despite the month's heat, minimum temperatures fell into the 40°s or 50°s on fifteen days. On twelve of those days, lows at traditionally cooler valley locations in the north fell to 55° or lower. The coolest morning of July was the 1st with Pequest (Warren) at 46°, Walpack (Sussex) down to 48°, and Basking Ridge (Somerset) at 49°. Walpack took low honors on the 2nd (52°), 6th (54°), 9th (55°), 10th (52°, shared with Pequest), 13th (55°), 14th (49°), 15th (50°), 16th (54°, shared with Pequest), 17th (52°), and 31st (55°). Pequest took the honors on the 5th at 53°.

The bulk of July's rain fell in thunderstorms during the first and last weeks. Limited rain fell in the middle half of the month when temperatures were warmest, leading to a bit of a flash drought. Some locations went seventeen consecutive days without a drop of rain, bringing the flow of some rivers to below median levels for the first time since May. Storms on the 3rd into the 4th brought 2.52" to Berkeley Township (Ocean), 2.47" to Montague (Sussex), and 2.06" to Hillsborough (Somerset). While most areas did not see this much, there was a fair soaking in all but the southwest corner of the state in storms that occurred in the pre-dawn, mid-day, and evening hours. Trees and power lines were reported down in portions of Cape May, Ocean, and Warren counties. The early storms produced pea-size hail in Wantage (Sussex), the mid-day ones pea-size hail in Holland (Hunterdon), and hail up to an inch in diameter was reported in Jackson Township (Ocean) and Manalapan (Monmouth) in the evening.

The 6th saw storms in the Rt. 195 corridor, with Mansfield (Burlington) receiving 2.80" and Wall Township (Monmouth) 1.00". Stone Harbor (Cape May) also had 1.47". Tree and wire damage was reported in Mercer, Burlington, and Monmouth counties. More storms on the 7th brought 3.69" to Oswego Lake (Burlington), 2.49" to Chesterfield Township (Burlington), and 2.03" and 1.88" to stations in Hamilton Township (Mercer). Again, trees and wires went down in Camden, Gloucester, Burlington, Monmouth, and Ocean counties and rice to quarter-size hail were reported in Tabernacle (Burlington), Readington Township (Hunterdon), Whitehouse Station (Hunterdon), and Hillsborough (Somerset). South Jersey was drenched on the 8th with 4.05" in Woodland Township (Burlington), 3.84" and 3.77" at two Medford Township (Burlington) locations, 3.82" at Berlin (Camden), and 3.13" in Estell Manor (Atlantic). There were power outages in Cape May (Cape May), while winds felled trees in six northern and central Jersey counties.

During the mid-month dry spell, light rain producing storms resulted in tree damage in Essex, Passaic and Bergen counties. The northern border areas received 0.44" in West Milford (Passaic) and 0.35" at Wantage (Sussex) on the 18th, and the southern third saw 1.69" in Buena Vista Township (Atlantic), 1.57" at Mantua Township (Gloucester), and 1.56" in Woodbine (Cape May) on the 19th.

Almost daily storms roamed parts of the state during the final week, with the 24th bringing Sea Isle City (Cape May) 2.45" and Woodbine 1.95". The northwest was wettest on the 25th, with Stockton (Hunterdon) coming in with 1.80", Bethlehem Township (Hunterdon) at 1.76" and Greenwich Township (Warren) with 1.74". Areas north of Rt. 80 saw the rain on the 26th, especially in Sussex County with 0.71" at Hardyston Township, and 0.69" and 0.68" at locations in Wantage. The final storms of the month on the 29th into the 30th brought rain statewide, the heaviest falling in Ocean (Lavellette: 2.35") and Monmouth (Howell: 2.34") counties.

Fog was heavy in some locations on the morning of the 4th, especially in central NJ. Coastal locations reported fog on the 21st and 22nd, with Highlands locations a bit fogged in on the mornings of the 24th, 26th and 29th.

The local strong winds accompanying some thunderstorms happened to miss the many anemometers scattered throughout the state. Only the Atlantic City Marina (Atlantic) recorded a gust as high as 40 mph, this occurring on the 11th. The 29th was the windiest day, with a 38 mph gust at Cream Ridge (Monmouth) and seven other stations with gusts exceeding 30 mph. Barometric pressure was at a maximum on the 17th, with readings from 30.25"-30.30" and lowest on the 26th at 29.60"-29.65".

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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