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August 2023 Weather Recap: Protective Bubble Keeps Searing Heat Away From NYC
October 2023 Weather Recap: Warm Beginning & End

September 2023 Weather Recap: 2nd Rainiest September on Record

  Sept 29 2023 rainstorm_map1-abc-ml-230929_1695989164289_hpEmbed_16x9

After a very warm and dry start, September 2023 ended cool and very wet.  The six-day period Sept. 3-8 all had highs of 88° or hotter, with an average high of 91° (eleven degrees above average).  Then the eight-day period Sept. 23-30 all had highs of 66° or cooler, with an average high of 64° (eight degrees below average).  Temperature-wise, the two periods balanced each other out and the month ended up with a close to average temperature (+0.2 degrees above average). 

 

After having no days in the 90s in August, September had four, the most in September since there were six in Sept. 2015.  The four days in the 90s were consecutive, making this the only heat wave of the year.  And with highs of 93°, Sept. 6 and 7 tied July 5 for hottest reading of the year.  (9/6, with a high/low of 93°/77° had the hottest mean temperature of the year.) 

 

Despite there being no measurable rain in the first week of the month, September 2023 ended up being the second rainiest September on record with 14.25" measured  (September 1882 had 16.85") - and the fourth wettest of any month.  More than half of the rain (8.90") fell in the last eight days of the month. (This amount alone would have made it the 10th wettest September.)

 

Chart - 5 rainiest months on record

 

Five days had more than an inch of rain (and another had 0.96"), the most in one month since August 2011 which had six.   The rainstorm of 9/29 produced 5.48" of rain (much of it in a 3-hour period), the ninth greatest amount to fall on a calendar date.  Tropical storm Ophelia impacted NYC's weather for four days (9/22-9/25) and produced 3.00" of rain, close to what fell in just two hours on 9/29.

 Chart - Sept 2023 Daily Rainfalls of 1 Inch or More

The last 16 days of the month all had below average mean temperatures, the longest below average streak since April 2020, which also had a 16-day streak in the month's last 16 days (a streak of 22 days, occurred in March 2018).  Additionally, the last eight days all had highs in the 60s, the longest such streak in September in the years since 1960 (the coolest reading of the month, 50°, was reported on 9/27).  For the entire month there were 10 days with sub-70 highs, which was the most in September since 2006.  

 

In total, there were 12 days with highs in the 90s in 2023, the fewest since 2014, which had eight.  The last time a summer had its hottest reading at 93° or cooler was in 2014 when it was 92°.

 

Of the 23 years in which August had no readings in the 90s, September 2023 had the second most highs in the 90s (Sept. 1915 had the most - five)

 

Here are recaps from nine previous Septembers:

2022

2021

2020

2019

2018

2017

2016

2015

2014

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