Summer

A Return to Hot Julys After a Two-Year Respite; Awfully Wet Too: July 2016 Recap

August 3, 2016 - 5:01pm -- Dave Robinson

Flooding photo

The second half of the 2016 NJ weather and climate year began with plenty to talk about. Maximum temperatures were 90° or higher somewhere in the state on 20 afternoons. This, along with many warm nights, helped boost the mean monthly temperature into the top 10, based on statewide records back to 1895. Yet, remarkably, this was only NJ’s 5th warmest July in the past 11 years. The 77.2° mean was 2.2° above the 1981–2010 average.

On 15 July days an inch or more of rain fell somewhere in NJ. This included eight days with greater than 2” in spots and four days where a few locations exceeded 4”. Statewide, the average rainfall was 6.85”. This was 2.33” above average and ranks as the 14th wettest July since 1895. It was the wettest July since 2004, and the 4th wettest in the past 41 years. The northern half of the state (Mercer/Somerset/Union northward) averaged 7.27” (+2.49”, 14th wettest), while the southern region averaged 6.77” (+2.38”, 12th wettest). This all came in a month where the northern half of the state remained classified as being in moderate drought (D1) on the US Drought Monitor, with about half of south Jersey considered abnormally dry (D0). Also, on July 26th the NJ Department of Environmental Protection placed the northern half of the state in a drought watch. These actions were the result of notable rainfall deficits dating back to the early spring, with the warmth of the month exasperating low soil moisture, stream flow, ground water, and reservoir conditions. Clearly, the late-month heavy rainfall in a good portion of the state warrants a re-evaluation of drought status as NJ heads into August.

Rather Dry, but Still Some Storms: June 2016 Recap

July 6, 2016 - 1:58pm -- Dave Robinson

Tipped helicopter

Despite some damaging storms impacting portions of New Jersey on several days and some localized deluges near month’s end, June rainfall came in well below average. The statewide average of 2.36” was 1.66” below the 1981–2010 average. This ranks as the 20th driest June since 1895. Northern and central counties were generally drier than those to the south. At month’s end, the counties from Hunterdon, Somerset, and northern Middlesex northward were classified as being in “moderate drought,” the D1 category on the US Drought Monitor. The counties to the south, through Ocean and Burlington, were in the Monitor’s “abnormally dry” D0 category. June stream flow, ground water, and precipitation levels were all well below average, while reservoir capacities in the north began to dip below average near the end of the month.

Temperatures began on the cool side, but the second half of the month was warm enough to bring the statewide average June temperature to 70.6°, which was 0.5° above average. This ranks as the 30th mildest June on record. There was one minimal heat wave at some inland lower-elevation locations, where temperatures climbed to 90° or higher from the 19th–22nd. However, no location exceeded 93° this month. The dry conditions helped to rid the atmosphere of the previous day’s warmth during the nighttime hours, thus temperatures of 45° or lower were observed in spots on seven mornings.

With an El Niño underway, how much of an impact can we expect it to have on NJ's summer weather?

July 23, 2015 - 2:29pm -- Dave Robinson

Sea Surface Temperature (SST) anomalies for July 20, 2015.  NOAA/NESDIS.

Scientists are carefully monitoring sea-surface temperatures in the tropical Pacific Ocean for a potential El Niño event. An El Niño occurs when warmer-than-average waters start to form in the eastern Pacific Ocean, specifically near the equatorial latitudes. Easterly winds (blowing from the east) typically move warmer water to the western Pacific (near Indonesia), permitting cooler water to upwell to the surface in the east (near South America). When these winds are weaker, or if they reverse direction, the warm water stays in the eastern Pacific. This difference in sea surface temperatures and winds creates a new dynamic between the ocean and atmosphere, distinctly affecting weather patterns across the world. No two El Niño events are alike; they vary in magnitude and location of the largest temperature anomalies. El Niño events can be classified as Strong, Moderate or Weak.

Warm Evenings in New Jersey

March 30, 2015 - 7:55pm -- Jack McCarty

Heat wave photo

Daily temperatures naturally fluctuate from week-to week and year-to-year (factoring out the seasonal “march” of temperature). Thus when temperature trends emerge over decades, it sparks a special interest here in the Office of the New Jersey State Climatologist. We are in the midst of a project to examine prolonged heat episodes throughout the state and have found some evidence for recent increases in such events. As impressive winter cold slowly comes to an end in NJ is there a better time to present some of our heat results? Of course not!

Our study involves examining daily maximum and minimum temperatures for seven stations distributed across the state, each with 100-plus years of records. This study began last summer with an evaluation of New Brunswick heat events. We showed that New Brunswick has had an increase of daytime heat events in recent decades and nighttime heat events are becoming more commonplace. In the course of expanding our analysis to seven stations, we have found larger changes in warm nighttime temperatures than in hot daytime temperatures. Excessively warm nighttime temperatures typically get overlooked when discussing potentially dangerous heat episodes, yet they can bring about dangerous health concerns for those unable to escape persistent warmth.

Heat Events in New Brunswick: A Climatological Analysis

September 16, 2014 - 1:27pm -- Jack McCarty

Heat wave photo

The summertime in New Jersey is characterized by warm temperatures that give some relief from cold and dreary wintertime conditions. However, amongst pleasant summer days, the atmosphere can align in a way that makes the heat on other days rather unbearable — something that we commonly refer to as a heat wave. Heat waves have a large impact on public health, utilities, infrastructure and more, which is why we often hear the media discussing heat waves across the nation. While heat waves may call for a day at the beach, they're also a cause for public concern.

Comfort Reigns: August and Summer of 2014 Recaps

September 3, 2014 - 5:50pm -- Dave Robinson

Surf photo

A month ago, many NJ residents felt July was quite cool, while in fact it was just 0.4° below the 1981-2010 mean. Such was not the case in August, which truly was on the cool side. The statewide average temperature of 71.0° was 2.4° below average. It ranks as the 32nd coolest since 1895. Even when compared to the 1895-present mean, the month was 1.5° below average. Days with a maximum temperature of 90° or greater were hard to find, certainly a characteristic of the summer of 2014, which will be discussed later in this narrative.

Precipitation varied widely across the Garden State in August, rather typical of a summer month in these parts. Individual station totals ranged from 12.33” in Lacey Township (Ocean County) to 1.01” in Hillsborough (Somerset). When monthly totals from several dozen long-term stations were averaged together, the statewide precipitation was 4.39”. This is 0.18” above the 1981-2010 mean (0.26” below the 1895-present mean) and ranks as the 53rd wettest of the past 120 Augusts. It must be noted that the heavy rain that fell after 8 AM on the 31st is not accounted for in most August station totals. For the monthly state average, only several stations that observe at midnight have their full August 31st totals included, while monthly totals at most other National Weather Service Cooperative stations only run through the morning of the 31st. For more on this observing practice, see the April 2014 report.

So this is how a normal July feels...

July 27, 2014 - 8:45pm -- Dave Robinson

Beach sunset photo

Another comfortable mid-summer air mass is destined to invade the Garden State this week. This arrives on the heels of several other mild, dry air masses that have contributed to making this a rather average July in the temperature department. While many may think that this has been an exceptionally cool summer, it has not. However, given that the most recent four Julys all ranked within the top six for heat dating all the way back to 1895, all are forgiven for any misperception!

The overall pattern that has led to temperatures more often being on the cool than than warm side of the ledger since last fall is one of pronounced waviness in the jet stream, with a resultant tendency for a ridge (northward swing) in western North America and a trough (dip in the jet) in the east. This allows cool and dry air to infiltrate our region, with warm and humid air kept at bay to the south. It has also kept the west in severe drought and plenty warm.

Potential El Niño could impact New Jersey weather this summer

May 30, 2014 - 5:11pm -- Dan Zarrow

Map of impending El Nino

As climatological summer and the Atlantic hurricane season begin on June 1, scientists are carefully monitoring sea-surface temperatures in the tropical Pacific Ocean for a potential El Niño event. An El Niño occurs when warmer-than-average waters start to form in the eastern Pacific Ocean, specifically near the equatorial latitudes. Easterly winds (blowing from the east) typically move warmer water to the western Pacific (near Indonesia), permitting cooler water to upwell to the surface in the east (near South America). When these winds are weaker, or if they reverse direction, the warm water stays in the eastern Pacific. This difference in sea surface temperatures and winds creates a new dynamic between the ocean and atmosphere, distinctly affecting weather patterns across the world. No two El Niño events are alike; they vary in magnitude and location of the largest temperature anomalies. El Niño events can be classified as Strong, Moderate or Weak. What might an El Niño summer mean for New Jersey's weather?

No escaping a sultry, sweaty heat wave

July 22, 2013 - 8:09pm -- Dan Manzo

Garden State residents suffered through another heat wave last week, and at times it seemed like the unrelenting heat would never subside. A heat wave is unofficially defined as three or more consecutive days with the maximum temperature at or over 90°. This heat wave lasted seven days for many areas and furthermore, very high dew points (a measure of moisture in the air) made the heat index soar above 105°.

The heat wave began for many on Sunday, July 14, with stations in central and northeast Jersey, such as Haworth, Jersey City, New Brunswick, Howell, and Toms River all recording high temperatures in the low 90°s. Hawthorne was the hottest spot with a high temperature of 94°. Other stations recorded high temperatures in the upper 80°s. This combined with widespread dew points above 70° resulted in heat indices at or near 100°.

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