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October 2015

October's First Autumn Chill

30s

 

I don't know about you, but I find adjusting to the season's first chilly temperatures in the fall a more challenging than adjusting to warm weather in the springtime.  In the fall of 2015 the temperature fell to 35° on the morning of Oct. 19, which was the earliest it was this chilly since 1976, when the low on the same date was 34°.  Mornings in the 30s in October occur infrequently in New York City, with a typical October seeing just two such days.  The average date for the first low in the 30s is Oct. 23.  It's happened as early as Sept. 30 (in 1912) and as late as Nov. 15 (1938).  On average, October's coldest reading is 38°, with the coldest being 28° in 1936.  The mildest chilly reading, 45°, occurred in 1971 and 1946 (more recently, October 2004's chilliest reading was 44°). 

 

The greatest number of lows in the 30s has been nine, in 1925.  One in eight Octobers have had lows of 32° or colder; however, the last time it happened was in 1988 (the coldest temperature in recent years was 33° in 2011).  At the other end of the temperature spectrum, one in four Octobers have had no readings in the 30s (most recently in 2017, 2014 and 2013).  Here are some other observations:

 

  • Two periods have had considerably more 30-degree days than other years.  The years between 1922-1940 averaged 3.9 30-degree days in October.  This followed the years 1910-1921, which averaged only 1.4 such days.  Then there were the years between 1964-1988, which averaged 3.2 chilly lows; since then the average has been half that, 1.6.
  • October 1974 and 1925 were noteworthy for having three days in a row with lows of 32°  or colder.  And October 1940 and 2011 distinguished themselves by having five days in a row with lows in the 30s. 
  • The most consecutive years with Octobers that had no readings below 40° is three: 1994-1995-1996.

 

Clipart_sweater

 

  • The second latest date for the first reading in the 30s, Nov. 13, 1946, was sandwiched between two years with the earliest dates for this occurrence - Oct. 1, 1947 and Oct. 4, 1945.
  • After having the earliest temperature in the 30s on record, Sept. 30 in 1912, October had none.
  • Finally, there have been two high temperatures in the 30s in October: on Oct. 26, 1962 (39°) and on Oct. 30, 1925 (38°).

 

Autumn.washington.square.park

 

 

 

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Record Highs & Lows: The Home Runs of Weather Reporting

Record.cold Record.heat

 

Because of the excitement they generate I like to think of record high and low temperatures as the home runs of the weather world.  Since weather records for New York go all the way back to 1869 it's a challenge for new ones to be set.  Still, since 2000 (thru 2018) there have been 82 records set or tied, which is about four every year (in 2018 two new record highs were established and two were tied).  However, only nine of the 82 were record lows (most recently on Nov. 11, 2017).  Here are some other interesting facts about New York's temperature extremes:

 

  • The oldest-standing record is the record low of March 1 which goes all the way back to the first year of record keeping, 1869.  The oldest-standing record high occurred nearly as far back, on Jan. 23, 1874.  The newest record (thru the end of 2018) was set on May 3, 2018 when the high reached 92°.
  • 22 record highs and 91 record lows stand alone, i.e. not shared with other years.  The most years tied for a record on one date is six, for record lows on three dates: March 3 (11°), June 2 (48°) and Sept. 8 (54°).  (Ties would be less prevalent if daily temperatures were reported to one decimal point.)
  • There are 21 current records that broke a record set the previous year (12 for lows, nine for highs).  The most recent occurrence was in 1994 when the record high on June 19 broke the previous record set the year before.

 

Ice.surrounds.manhattan

 

  • The most that a record beat the previous record by was 19 degrees on Sept. 7, 1881 (101° vs. 82°).  There are 31 current high temperature records that beat the previous record by 10 degrees or more.  The most recent happened on Feb. 21, 2018 when the new record high was 10 degrees above the previous record (78° vs. 68°).  Eight record lows exceeded the previous record by 10 degrees or more, with the largest difference being 14 degrees on Dec. 18, 1919 (-1° vs. 13°).
  • Of the 150 years since 1869, three had no record highs or lows: 1870, 1958 and 1992.  The year with the most records was 1888 when 49 were set (38 were record lows, 11 record highs).  In recent years the year with the most records was 2001, which had 15 (14 record highs, one record low).  These figures reflect records that may no longer be valid, with many broken in subsequent years.  Looking at records that are still standing, 1888 still has the most, but the figure is 18; it's tied with 1875.  
  • The mildest reading for a record low is 59°, and it has occurred twice - on July 29 (in 1914) and on Aug. 1 (1964).  The lowest temperature for a record high is 54°, which was set on Feb. 7, 1938.  
  • Finally, New York's all time hottest and coldest temperatures occurred just two years apart, in 1934 (-15° on Feb. 9) and in 1936 (106° on July 9).

 

Hotday.newyork.washsquarepark

 

Chart - record highs and lows

 

(This post was inspired by an in-depth compilation of data supplied by Eugene De Marco, another New York City weather hobbyist.)

 

     

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New Record Set for Most Days with Highs of 80 Degrees+

80s

 

1944 ceded its #1 position to 2015 twice in regards to warm-temperature records.  First to fall was a streak of 80-degree+ days, which 2015 topped by three days (62 vs. 59); then a few weeks later 2015 once again passed 1944, this time to become the year with the most total days above 80°; by the end of September the number had risen to 114 vs. 1944's former top total of 108.

 

114

 

In a typical year nearly one-fourth of the days have highs in the 80s, but in 2015 one-third were 80°+.  However, the number of those days that were in the 90s was just slightly above average (20 vs. 17), ranking it 32nd among all years since 1900.  Among the ten years with the most 80°+ days (see chart below), 2015 had the fewest that were 90° or hotter.  As a result, the average temperature of 2015's days that were 80° or warmer was lower than all the other years (by one to three degrees). 

 

2015 set one more record pertaining to 80°+ days as every day in  August had highs of 80°+.  Previous to this year the most 80° days in that month was 28.  This tied July 1944 as the only month to have every day in the 80s or warmer.  (And May 2015 set the record for most 80-degree days in May, with 18.)

 

MOST 80-DEGREE+ DAYS
(Since 1900)
       
  # of Days Average 
  80+ 90+ High
2015 114 20 85.2°
1944 108 37 87.5
1991 105 39 87.8
1959 104 27 86.6
2005 100 23 86.3
1949 100 29 86.5
2010 99 37 88.1
1983 98 36 87.8
1966 98 35 87.9
1941 98 29 86.4
       

 


A Trend Towards Fewer Cool Summer Nights (Lows in 50s)

Cool-and-drops

 

In the decades between 1910-1980 the average number of days with morning lows in the 50s during the summer (mid-June thru mid-Sept) was twelve.  Since then the number has fallen sharply, and in the current decade (thru 2019) the average has fallen to 3.4 days.  In 2016, for the first time, there were no lows in the 50s during the summer (1966 had one and six summers have had  two such days, including 2015).  The greatest number occurred in 1940 when there were 33 days.  In recent years the most 50-degree readings was 19 in 1986, and 13 in 2007 (which is the only summer in the past 21 years to have more than 10).  Since 1991 twelve summers have had no lows in the 50s in July or August (including 2014 thru 2019).  There were ten such summers in the years between 1910 and 1990.

 

AVERAGE NUMBER OF 50-DEGREE LOWS 
EACH SUMMER BY DECADE
  2010-2019      3.4
2000-2009      6.4
1990-1999      8.2
1980-1989      8.9
1970-1979    10.8
1960-1969    12.6
1950-1959    11.3
1940-1949    12.6
1930-1939    10.0
1920-1929    16.3
1910-1919    15.1
     
FEWEST/MOST COOL SUMMER NIGHTS
(June 16 - Sept 15)
         
Fewest   Most
1966 1   1940 33
2015 2   1963 27
2011 2   1927 25
1996 2   1926 24
1993 2   1914 24
1983 2   1946 23
1931 2   1918 22
2019 3   1924 21
2013 3   1962 20
2005 3   1986 19
1981 3   1965 19
1971 3   1915 19
1961 3      
Average =  11

 


 

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September 2015 Weather Recap: New York's Warmest on Record

Trophy.winner

 

After experiencing near record-warmth in May (second warmest) and August (third warmest), 2015 can now lay claim to the warmest September on record, easily topping 1961's previous record by 0.9 degrees.  Like much of the summer, September's average temperature was greatly influenced by the lack of any incursions of chilly air masses.  The coolest reading was 56°, which matched Sept. 1921 for the mildest minimum reading for the month.  (September's coolest reading is typically around 49.)  And only five days had lows in the 50s, which was well below the average of 13.  Finally, the month joined Sept. 1968 and 1921 as the only Septembers to have no high temperatures cooler than 70°.  A typical September sees five or six such days.  Other interesting facts:

 

  • Nine days had mean temperatures (average of the high/low) that were 10 degrees or more above average, but that was no match for the 14 such days in Sept. 1961.  (1961's average high was just 0.1 degree lower than 2015, but 2015's average low was 1.7 degrees milder.)
  • This September matched that of 2005 by having just one day with a below average mean temperature.  However, in 2015 that day was just one degree below average while 2005's was four degrees below the norm.  (And Aug. 2015 had only a handful of days that were below average, and they were all also just one degree below average.)
  • This was the first time since 1998 that September was warmer than June, which was close to average (74.4 vs 71.2).
  • Despite this year's record warmth, Sept. 1961 had more 90-degree days (8 vs. 6) while Sept. 2005 had more 80-degree days (23 vs. 19).
  • The hottest high temperature of the year occurred on 9/8 when the mercury reached a record 97 degrees.  (However, the year's highest mean temperature occurred on 7/20, with a high of 94/82).

 

Highline

 

  • The month saw the end of the longest streak of 80-degree days on record, 62 days.  Then shortly thereafter another warm temperature record was established - most total days  of 80-degree+ in a year (which grew to 114 days by the end of the month).  In both instances the previous record holder was 1944.  (Despite this record number of 80-degree days, 2015 ranks 12th for most lows of 70 or warmer.)
  • The month was on the dry side and featured a 15-day stretch with no rain (the second longest streak of the year).  In total 3.28" of rain fell, with most of it falling on two days - a record 1.51" on 9/14 and 1.27" on 9/30.  And although the month had below average rainfall (one inch below average), it had considerably more rain than any of the next eight warmest Septembers, which averaged just 1.58".

 

10 WARMEST SEPTEMBERS 
(Since 1900)
           
  Mean Average Max Min
 Year Temp High Low Temp Temp
2015 74.4 82.6 66.3 97 56
1961 73.5 82.5 64.6 95 49
2005 73.3 81.6 65.0 92 50
1959 72.3 80.9 63.6 93 46
1931 72.3 81.3 63.3 99 49
1921 72.1 80.7 63.5 96 56
1930 72.0 79.8 64.1 88 52
1983 71.8 80.5 63.0 99 49
1971 71.5 77.3 65.8 91 49
2010 71.1 78.7 63.4 96 54
           
Source: NOAA Local Climatological Data

 

 

 

 

 

 

 

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