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Climate: Summer 2004 Recap

Cool and dry east, cool and wet west, but late summer tropical weather narrowed the gap

By Edward Moran
Published on September 22, 2004

Climate articles:

The meteorological summer of 2004 (June, July, and August) featured a rather dry and cool weather pattern across most of Long Island. This was in sharp contrast to the very rainy summer experienced across New York City and the extreme western end of the island.

Cooler than Normal Temperatures

On most of Long Island the temperature did not reach 90 degrees all summer. The highest temperature at Islip was 87, which occurred on June 9 and again on June 18. In fact, barring an unusually hot autumn heat wave, those will be the only two days that the temperature at Islip exceeded 85 during all of 2004.

The entire region experienced a nearly complete lack of Triple-H (hazy, hot, and humid) weather for the summer of 2004, although a couple of days in late August came close. At JFK Airport, the temperature reached 91 degrees on June 9 for the only 90 degree day of the summer. Central Park reached or exceeded 90 degrees on only 2 days, the highest temperature also being 91 on June 9. In general, June 9th was the hottest day of the summer season across most of the region, but also featured relatively low humidity. As seems to be traditional, LaGuardia Airport and especially Newark Airport in New Jersey were isolated islands of heat this summer and recorded several more days of 90 degree heat, although still much below normal for those locations as well. The chart above summarizes the distribution of the hottest days of the summer.

Late Summer Tropical Rains end the dry spell on central and eastern Long Island

Rainfall totals for Long Island and NYC area stations, June - July - August 2004 Although relatively cool, most of the summer was dry enough across Long Island to require frequent irrigation of lawns to keep them from turning brown. On the plus side, through the middle of August nearly all of the weekend days were rain free. One exception occurred on Saturday July 24th when widespread, although not particularly heavy rain fell across the island. In fact, other than the very heavy rain that fell on much of central and eastern Long Island early on the 13th of July, there was a noticeable lack of significant rainfalls through the middle of August.

Through mid August, New York City received nearly three times as much rainfall for the season as central and eastern Long Island. A persistent pattern in the eastern US resulted in numerous cold frontal passages throughout the summer. While many of these fronts were accompanied by heavy rains, for the most part the associated showers and storms trained along the same path just to our west all summer. On July 27, very heavy rain caused significant flooding in Nassau County and points west while more moderate rains made it as far east as a line stretching roughly from Babylon to Port Jefferson. East of that line rainfall was generally very light, mostly a tenth of an inch or two. This scenario was repeated several times over the course of the summer. The image to the right, which shows the Radar estimated rainfall totals for Long Island, August 11, 2004 radar estimated rainfall for August 11th, is representative of many of the summer's rain events.

During mid and late August the weather became generally more humid across the island and for the first time all summer rainfall exceeded normal across central and eastern Long Island. This was mainly due to rainfall from tropical cyclones (Bonnie and Charley) that moved north through the eastern United States after making land fall in the southeast. During the period from August 13th (when some rains from Bonnie reached our area) through August 31, 4.61 inches of rain, more than half of the total received this summer, was measured at Islip.

In fact, the defining feature of the local weather from mid August right through September has been the contribution of numerous tropical cyclones to heavy rainfall in our area. While these storms have been landfalling in the Deep South, the northward migration of their remnants has contributed most of the rainfall that we have received in that period. To date, we have received rains from Bonnie, Charley, Gaston, Frances, and Ivan.

The remnants of Hurricane Charley in particular were responsible for much of the rain which fell on Long Island during August. Although Charley was officially still a minimal tropical storm as its center passed over Long Island, winds remained mostly light as they were confined to a very small area very near the core, with a few areas reporting wind gusts near 30 miles per hour.

During September, the remnants of Hurricanes Frances, Ivan, and Jeanne all contributed heavy rainfalls and strong wind gusts in our area as the active tropical pattern continued unabated from mid August through the end of September. Long Island once again avoided direct impacts from a hurricane. There hasn't been one since the center of Hurricane Bob brushed Montauk in 1991, but it will happen again eventually...

Long Island rainfall amounts associated with Tropical Cyclones:
Rainfalls on Long Island associated with Tropical Cyclones - 2004