A Mainly Dry and Warm September in the Northeast

Posted: October 11, 2017, 10:01 am by chewitt

What a flip-flop of a month September was! While August gave us the impression summer really wasn’t going to make a comeback, September brought back the real dog days of summer. While we were initially cool with tropical influences, the second half of the month was a near non-stop stretch of warmth and largely dry weather.

Much of the country was focusing on the disaster Harvey left behind in Houston to start the month, but the system itself was finally moving away from Texas toward the Ohio Valley. Much of the storm broke up rather quickly with pockets of precipitation making their way into the Northeast, with major cities not exceeding an inch of rain. Many areas north of the Mason-Dixon Line were cool with temperatures not really breaking out of the 60s and 70s. Just a handful of interior locations just broke their record lows, one of which included Hartford, CT at 41 degrees on the 2nd.

A line of thunderstorms did make their way into the region on the 5th, which resulted in our only “severe” weather day of the month. The front stalled on the 6th, which let several systems ride up the East Coast. But just like the remnants of Harvey, the majority of the rainfall stayed under an inch. Eventually, high pressure worked its way back in and a stretch of dry weather began.


Leaves finally changing near Augusta, Maine in late September. 


Like Harvey, Hurricane Irma stole the attention of the nation as it made its way into Florida during the middle of the month. The remnants of that system were largely suppressed by the aforementioned high pressure system, with only a few showers working into the Mid-Atlantic States on the 13th and 14th. Otherwise, the Northeast was quiet for a while, with only a few noteworthy events such as a renegade shower dropping 2.5” in just 30 minutes on Philadelphia International airport.

Hurricane Jose gave us a brief scare but largely remained offshore, with its outer bands and swell mainly impacting the shores of New Jersey, Long Island, and southeast New England. It meandered for several days before finally dissipating and moving east, away from the U.S. on the 22nd. This was followed by a quick disturbance at the end of the month that brought some rain (and even some flooding issues) in New York and southern New England.



Jose's swell on September 19th splashing up in Brooklyn Bridge Park


Throughout virtually the whole period after the 10th, each day averaged 5 to 15 degrees above normal across the Northeast. Many locations were well into the 70s, 80s, and even low 90s. The added humidity did not help things either. Thus, what should be the first month of meteorological fall ended up feeling like July at times. Several high temperature records ended up being shattered. In particular, between the 24th and 27th, New England broke several, reaching the upper 80s and low 90s including Hartford topping 92 degrees on the 27th. New York City had only one record high temperature on the 24th at 91 degrees.

Overall, the region was 1.5 to as much as 4 degrees above normal for the month (with most of the record breakers in New England and upstate New York). And while September can be dry without tropical moisture, precipitation was still fairly hard to come by in many areas away from the shorelines with rainfall deficits of nearly 2 inches.

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