New York City Weather Archive

Lackluster Heat Waves

This post was inspired by this week's rather tepid four-day heat wave (Aug. 5-8, 2018), which had an average high of 90.8 degrees (with highs of 91, 92, 90 and 90).  Of the 66 four-day heat waves that have occurred since 1870 only one, in July 1896, had a lower average high, 90.3 degrees.  (2018's low-grade heat wave matched one in August 2009.)  On average, four-day heat waves have had an average high close to 94°.  (The hottest four-day heat wave on record took place in the summer of 2010, when the high temperature from July 4-7 was 99.5 degrees.)

 

 

 

 

However, the story changes when low temperatures are included in the analysis.  For example, this August's heat wave had an average low of 75.0 degrees, which was 1.3 degrees warmer than the average four-day streak and warmer than two-thirds of the four-day heat waves examined.  When combined with the average high, the mean temperature ranked as 27th coolest - quite a difference in ranking compared to its average high alone.  (This follows the weather storyline of this century whereby nighttime temperatures in New York are warming more than daytime temperatures.)

 

 

Finally, while the typical four-day heat wave had a 20-degree difference between its high and low, this August's was 15.8 degrees apart, which was the third smallest diurnal variation of the heat waves studied (a heat wave in July 1995 had the smallest, 14.7 degrees, while the second smallest was in July 1870).  

July 2018 Weather Recap: Hot Temperatures, Followed by Torrents of Rain

If July 2018 were a cocktail its ingredients would be one part heat, three parts rain.  After a hot start, with temperatures nine degrees above average during the month's first five days (average high/low was 92/78), the rest of July was seasonably warm, which moderated the month's average temperature to 1.1 degree above average.  As for the rain, after a dry start, with just 0.24" measured through July 11, the skies opened up and the rest of the month was very rainy, with 7.21" measured.  With 7.45" in total this was the rainiest month in more than four years, since April 2014, and the rainiest July in fourteen (and the fourteenth wettest July on record).

 

In late July there were seven days in a row (July 21-27) in which measurable rain fell.  This was the fourth streak of six days or more this year, joining 1989 as the only two years since 1900 with four streaks of six days or longer.  (Besides the persistent rain, dew points throughout this week-long period were in the uncomfortable 72°-74° range.)

 

 

The seven-day streak with rain was the first since 2012, but this year's had considerably more rain (2.89" vs. 0.86").  The last streak of seven days or more with more rain was in May 2009, when 3.81" fell.

 

Downpours on 7/12 and 7/30 were confined to upper Manhattan; Central Park had 0.71" and 0.37", respectively, but my neighborhood, Greenwich Village, four miles south of the park, was dry.  And during the afternoon of 7/17 Manhattan was the bulls-eye for torrential rain from a severe thunderstorm, with 2.24" pouring down in little more than an hour.  Conversely, on 7/27 thunderstorms during late afternoon thru evening produced more than an inch of rain in most parts of the metro area (and 3-5" in parts of east-central NJ) but Central Park had only 0.25". 

 

July's rainfall in Central Park was considerably more than the three other reporting sites in the metro area:

 

 

 

Other July observations: 

• Four of the first five days in July had highs in the 90s; the only one that didn't was the 4th of July, but its high of 86° was the warmest reading on this holiday in five years.  However, due to its very warm low of 77°, the mean temperature was the warmest since 2010.

 

 

• Thirteen days in a row (July 8-20) had highs of 80° or warmer, the longest such streak since one of 19 days in August 2016.  (The record is 62 days in a row, set three years ago.)

• What was most impressive about the hot beginning to July were the low temperatures, all  which were 76° or warmer.  This happens almost as infrequently as five-day streaks with highs of 95°+.

• This was the ninth July in a row with no lows in the 50s, the longest such streak in the years since 1900.  Before 1980 more than half of Julys had at least one low in the 50s, but since 1980 that portion has fallen to 25%.

• By July 25 the month had picked up more rain than the combined amount in May and June (6.80" vs 6.64").

 

Here are links to previous July recaps:

2017

2016

2015

2014

 

July 2017 Weather Recap: Somewhat "Ho-Hum"

The month of July, temperature-wise, was close to average (+0.3 degree), with slightly below average rainfall (4.19", more than half which fell in the first week).  Thru 7/22 temperatures were 2.3 degrees above average, but the final nine days were four below average.  Five days had highs in the 90s, which was below the average of eight.  Four of these 90-degree days were consecutive, from 7/19 thru 7/22, making this the third heat wave of the year.  It was then immediately followed by five days in a row with highs in the 70s, the longest such streak in July since 2009.  7/20's high/low of 94/77 tied 6/13 as the hottest day of the year.  Finally, the month's rainfall highlight was on 7/7, when 1.78" fell, much of it pouring down during a two-hour deluge before lunchtime.  Here are a few other observations:

 

• July 4th was the warmest in four years, but its high of 85° was two degrees cooler than Easter Sunday's.  However, it started off much warmer, with a low of 70° versus Easter's morning low of 59°.  (And it was 24 degrees warmer than Memorial Day.)

• Although the average low for July was 1.0 degree above average, the average high was 0.4 degree below average.  This somewhat mirrored June, which had an average high that was 1.1 degree above average and a high that was right at the average.

• July's rainfall could have been considerably more but strong thunderstorms on 7/17 and 7/21 stayed north and south of Manhattan, and a predicted nor'easter on 7/29 stayed too far south and east of the City.

• This was the eighth July in a row with no lows in the 50s, continuing the longest such streak on record (for the month of July).

• July 1940, 1954 and 1963 had more than twice as many 90-degree days than July 2017, but their average temperatures were slightly lower, due to their average low temperatures, which were three degrees cooler:

 

 

• July Fun Fact: July 1937, 1938 and 1939 all had the same average temperature (76.6 degrees).  

 

 

 

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Days of 95 Degrees+ and "Super" Heat Waves

The majority of days with highs of 90° or hotter in New York fall in the 90-92 range (56% to be exact).  And while the average number of 90-degree days each year is seventeen (including readings in the triple digits), the average number of readings that reach 95° or higher is just three (and about one out of every four years have had no highs that hot, including the summer of 2017).  The most in one year was sixteen, in 1955.  What follows are some more hot-Hot-HOT weather observations, best read in a well air-conditioned environment:  

 

• Eleven years (since 1872) have had ten or more days with readings of 95°+, with the most recent being 2002, which had 13.

• Although 1955 is the year with the most days with highs of 95° or hotter, it ranks 19th in total number of 90-degree days (with 25).  Incredibly, nearly two-thirds of its 90°+ days were 95°+ (the average is one-in-six).

 

 

• 1970 has the distinction of having the most 90-degree days, twenty-two, without any being 95° or hotter.  And not far behind are 1959, which had just one of twenty-seven days reaching 95/100+, and 1939, which had one of twenty-four.  The most consecutive years with no days of 95°+ is two, which has happened four times, most recently in 2003 and 2004.

• The greatest concentration of years with with well above-average number of days with 95°+ readings was 1952-55, when there were nine in 1952, twelve in 1953 and sixteen in 1955 (1954 had four, two of which were highs of 100°).

 

 

• Although 1917 had only six days in the 90s/100s, the last four, on consecutive days, were sizzlers, with highs of 98-100-98-98. 

• The earliest excessively hot days occurred on April 18, 1976 and April 17, 2002, both which had highs of 96°, and on May 19, 1962 when the temperature topped out at a blistering 99°.  On the late side, the high reached 99° twice on Sept. 11, in 1931 and in 1983; and on Sept. 23, 1895 the high was 97°.

• The most consecutive days with highs of 95° or hotter ("super" heat waves) is eight, in 1944.  There has also been a streak of six days (in 1953) and seven of five days in a row.  The last time we experienced a "super" heat wave of five days or longer was during the summer of 2002 (which is the only one among the eight lengthiest to have no highs in the triple digits).

• The hottest temperature ever recorded in New York, 106° on July 9, 1936, came in the middle of a three-day super heat wave, with the day before having a high of 97° and the day after, 102°.

 

 

• The hottest early "super" heat wave occurred in 1925 when highs of 99-99-98-96 were experienced from June 4 to June 7.  The latest was in 1895 when there was a streak of three days from Sept. 21 to 23 (95-95-97).

• In 1944, which had thirty-seven 90-degree days, the first twenty-four were below 95°, but then 11 of the next 13 were 95° or hotter (concentrated in the four weeks between Aug. 4 and Sept 2).

• Perhaps the most famous super heat wave was July 1977's, which coincided with NYC's infamous blackout.  However, although the blackout began on the first day of a nine-day heat wave, the five days in a row with highs of 95+ began the day after power was restored: 98-98-97-100-102 (July 15-19).  And after a one-day respite on the 20th (high of 92°) the next day's high jumped to 104°.  

• In less than six weeks in the summer of 1949 (July 3-Aug. 11) there were three three-day super heat waves: 99-102-95 (July 3-5); 97-99-95 (July 28-30); and 100-98-99 (Aug 9-11).

 

 

• Finally, the hottest super heat wave of four days or more was in 1993 when the five days from July 7-11 averaged 99.8°, with highs of 98-100-101-102-97.  Two years earlier there was another streak of five days in a row, from July 17-21: 96-99-96-100-102.  Then after a one-day break, when the high "cooled" to the upper 80s, the high on 7/23 was 99°.   (A three-day "super" heat wave on July 1-3, 1966 had an average high of 100.3°.)

 

 

 

 

 

 

   
(I owe a debt of gratitude to Eugene DeMarco, a follower of NYC Weather Archive, whose spreadsheet showing the 90-degree days of every year, made this analysis so much easier for me to do.)

 

 

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The Towering Clouds and Beautiful Sunsets of Summer 2016

I've always had an appreciation for clouds and sunsets.  Five years ago I probably wouldn't have been able to write this post because I didn't have my smartphone with its camera.  Now I'm able to snap photos at a moments notice, enabling me to capture this summer's overabundance of photo-ready thunderheads and stunning sunsets.  And because I live in the West Village I probably notice them more since the low-rise buildings make the sky much more accessible than in Midtown Manhattan.  I hope you enjoy the photo revue that follows ... 

 

 

The photo display begins with one of me on Memorial Day weekend. The setting sun produced a nice effect on the flowers along Hudson River Park.

 

Rays of the setting sun stream over Sheridan Square in Greenwich Village.

 

I took this photo during a June visit to Pittsburgh to see my mother. These clouds brought to mind those I'd often see over the Atlantic Ocean close to sundown from Fire Island.

 

Taken on July 1, this photo shows a thundercloud from a storm that struck half an hour earlier. Although it was around 9PM the top of the cloud was catching the rays of sun that was below the horizon.

 

Early evening sun filtered through a slate gray sky over Sheridan Square.

 

This isn't a cloud formation in New York but it deserves an honorable mention.  I snapped the photo of this breathtaking thunderhead during a weekend visit to south central Pennsylvania in the midst of a late July heat wave.

 

Taken from my kitchen looking east as the full moon was rising.

 

This was the view on 7/28 looking east from the 44th floor of an apartment building in the Upper West Side. The light pastel coloring was the result of a fire in a warehouse in Long Island City (Queens) an hour earlier.

 

Taken as I was walking home from work on 42nd St. across from Grand Central Terminal.

 

Looking west from Sheridan Square at around 6PM in mid-August. Seeing it I felt I was in the presence of the Divine.

 

Early evening on a hot day in mid-August. These mountainous clouds brought a quick downpour to upper Manhattan but not to Greenwich Village.

 

Similar view and thunderclouds as the previous photo but on a different day one month later.

 

The same cloud formation as it moved behind the apartment building at 10 Charles St.

 

Wispy and puffy clouds over the West Village.

 

Sunset on the Saturday of Labor Day weekend, taken on Christopher St. pier, which looks out across the Hudson River.

 

This is how the sun's rays from the above sunset reflected on the bank of towering clouds in the east.  Reminds me of rainbow sherbet.

 

I snapped this photo shortly after I came out of the Christopher St. subway station in the early evening. This view is looking east.

 

Taken the evening of Sept. 11 as I left the gym on Seventh Ave. South.

 

Taken on Sept. 14 close to the West Side Highway in Chelsea, shortly after a late afternoon thunderstorm. A few hours earlier the temperature was in the low 90s, the last 90-degree day of the year.

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6PM on Sept. 15, awaiting take-off at LaGuardia Airport.

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Lastlly, a golden sunset on Sept. 17 during a visit to my old neighborhood in McKees Rocks, PA.

 

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July 2016 Weather Recap - A Month in the Tropics

As we entered the last week of July it appeared the month's headline story would be about the heat, which took hold in the second half of the month.  But when three one-inch rainstorms occurred in the last week, the month's storyline became the combination of heat and rain.  A hot July is usually on the dry side (with rainfall about 30% below average), while a rainy July is cooler than average (by one or two degrees).  July 2016, however, was an anomaly in that it was the 21st wettest and 22nd hottest (going back to 1870). 

 

WELCOME RAINFALL

The 7.02" of rain measured in Central Park made July the rainiest month since April 2014.  It was also the wettest July since 2009.  Additionally, the month's rainfall was more than what fell in the previous twelve weeks (since April 10).  Finally, only one July has been hotter and wetter than this July - July 1988, which had 8.14" of rain and was 2.7 degrees hotter than average (see chart at bottom of page).  In addition to the three one-inch rainfalls at the end of the month, a rainstorm the began the night of July 4th (after the Macy's fireworks exhibition had ended) and lasted through the next morning also delivered more than an inch.  And while this rain helped reduce the year's rain deficit (which was also an issue last year), it was still four inches below average at the end of the month (13% below average).

 

HOT, BUT DON'T BELIEVE THE HYPE

The month began with three days in a row with highs in the pleasant 70s, the first time since July 1960 that the month started this way.  Then from July 14-30 the average high/low was 90/73, 4.5 degrees warmer than average.  And fifteen days between July 6-29 had highs of 88° or hotter.  Additionally, eight days had lows of 75° or warmer, with the warmest being 80°.

 

 

After having no 90-degree days in June, July had ten (the average is eight), with seven occurring in an eight-day span from 7/21-28.  The one day that didn't reach 90° had a high of 89°.  If the temperature had reached 90° on that day (as it did at Newark and LaGuardia Airports) we  would have had an eight-day heat wave, which would have been the longest since 2002.)  The hottest day of the month was July 23, with a high/low of 96/80, eleven degrees above average.  However, July 25, with a high of 93°, felt hotter because it was much more humid and the heat index reached 102° (the feel-like temperature on the 23rd was actually 94° because of low humidity.) 

And while the second half of the month was hot and sultry, it was over-hyped by the media and some meteorologists, who put a sinister spin on the term "heat dome", leaning heavily on the global warming angle.  (I was interviewed on TV about the heat wave and I played it down as nothing extraordinary, especially compared to truly brutal heat waves of the past.)

 

 

CLOUD-COVER CURIOSITY

Despite all of the rain, the month was very sunny.  On the National Weather Servce's scale of cloud-cover, where zero is clear skies and ten is overcast, the month averaged a 2.8, with 19 days having clear or sunny days (a rating of zero to 2).  However, what's very peculiar is that Newark and LaGuardia were much cloudier (6.3), but hotter.  JFK Airport also had a 6.3 but with slightly lower temperatures than Central Park.  Is this reality or is there a difference in the way Central Park scales cloud cover?  It seems counter intuitive that Newark and LGA, with so much cloud cover, would have 15 and 16 90-degree days, respectively, while sunny Central Park had "just" 10 hot days.  Another peculiarity is the fact that Central Park reported no thunderstorms in July but JFK and Newark had seven and LGA four.  Working in Midtown Manhattan, I heard thunder and saw lightning during a number of storms so I'm baffled by this.

 

 

Finally, despite how warm the month was (2.2 degrees above average), four other Julys since 2010 were hotter:  2015, 2013, 2011 and 2010.  And although July of last year was 0.1 degree hotter, this July had twice as many days in the 90s.

 

 

 

 

 

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The Summer of 1908's Puzzling Nighttime 'Heat Bubble'

Reviewing New York's weather statistics over the past 145 years reveals that the years before 1930 were noticeably cooler than the years that followed (especially after 1980), which have seen some of the warmest years on record.  But, curiously, a number of the summers during the first decade of the 20th century had uncharacteristically warm nights, in particular, 1908.  That year stands out for a seven-week period with unusually warm nighttime temperatures unlike any that have been experienced - even in recent years.  Although highs during those weeks were three or four degrees above average, the average low of 74.5° was eight degrees above average.  Between June 30 and Aug. 17, fifteen days had lows of 77° or warmer, eight of them of 80°+.  No other summer has had that many sultry low temperatures.  It was these lows that made July the warmest on record until 1952. 

 

Sultry low temperatures became more common after 1990, but not during the first half of the 20th century.  In addition, the diurnal variation in the summer of 1908 was very narrow, with high and lows on many days ten degrees apart or less (typical is about sixteen degrees).  What was it about the air masses or jet stream in July 1908 that prevented temperatures from cooling down after dark?  Was it a matter of air pollution/particles of soot that prevented the temperature from falling at night?  This holding onto daytime heat is a characteristic of global warming, but one hundred years ago it was unheard of.

 

 

The chart below compares July 1908's average high/low temperature to those of eighteen other hot Julys.  What it shows is that the average highs of these hot months were two or three degrees warmer than July 1908, but July 1908's average low was warmer than every hot July by that same margin, with the exception of July 2013, which had the same sultry low.

 

 

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As Seen on TV ...

On occasion I've been asked to provide my point of view about weather events on New York TV station WPIX.  PIX-11 news reporter James Ford came across my blog back in 2014 and has contacted me to occasionally give my historical perspective.  (What's made it easier for both of us is the fact that PIX's office is conveniently down the street from my office on 42nd St.)  Here are the eight appearances I've made (so far) including links to each :   

 

 

Nov. 10, 2014.  In my first appearance I was asked to comment about an approaching Arctic front that would drop temperatures to more than 10 degrees below average between the 13th and 22nd. At its coldest, the high/low on Nov. 19 was 36/22, eighteen degrees below average.

 

Jan. 8, 2015. Talking about another Arctic air mass (which had me wearing earmuffs).

 

Feb. 16, 2015. Here I am in front of my apartment building (it was President's Day) commenting about the coldest February since 1930.  As you can tell by the pained expression on my face, it was very cold, with a wind chill of 5 below zero at the time of the interview.

 

May 6, 2016.  Commenting about the cool, damp and overcast conditions during the first week of May.

 

July 22, 2016.  And here I am in front of Penn Station (my train to Lancaster, PA was leaving in 15 minutes) giving my perspective about a heat wave that I thought was over-hyped.

 

 

March 14, 2017 - I was asked to comment about the snowstorm that brought "only" 7.6" of snow rather than the 12-18" that was predicted (the storm produced a lot of sleet) and on the admission by the National Weather Service that it knew this was going to happen but decided not to lower snow totals.

 

July 13, 2017 - On the 40th anniversary of the Blackout of 1977 I was asked to provide some perspective about the heat wave that coincided with the event (which was one of the City's most intense).

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Jan. 30, 2019 - After an 18-month absence I was asked to comment about an approaching Arctic front. Shortly after this interview a blinding snow squall its arrival and the temperature plummeted from the low 30s to 6 above zero by midnight.

Hot, Wet New York Summers

During the summer months clouds, thunderstorms or winds coming off the ocean often prevent temperatures from rising into the 90s.  However, there are occasional stifling days when high temperatures and thunderstorms co-exist, creating tropical conditions that wouldn't be out of place in Bangkok or Manila.  On average New York experiences about four of these days every year; most occur in July and August.  These downpours are usually of short duration (15 minutes up to a few hours).  This post takes a look at some of these summertime days that featured a combination of wicked heat as well as heavy rainfall. 

 

In 2015 the most tropical conditions were experienced on July 30, 2015.  On that day a sultry high/low of 87/76 was accompanied by a series of downpours and thunderstorms that produced 1.95" of rain between 1:00 and 5:00 PM.  During a 20-minute period between 1:24 and 1:44 an inch of rain poured down.  Afternoon dew points were in the oppressive mid-70s and the heat index reached the mid-90s before the rain moved in.

 

Three days have had highs of 100° or hotter and thunderstorms:

• July 18, 2012 - High/Low of 100/73. 1.76" of rain fell from  severe thunderstorms that moved through between 2:30 and 5:00; most of the rain fell in the two hours between 2:40 and 4:40.  By 4:00 the temperature had fallen to 73°.  Before the storms moved in the heat index was close to 110° and during the early part of the thunderstorms the dew point was in the mid-70s.

• July 21, 1991 - High/Low of 102/74.  0.46" of rain fell during a thunderstorm between 5-6PM.  The heat index was between 105° and 110°.

• July 14, 1954 - High/Low of 100/69.  0.37" of rain fell during thunderstorms between 9:30-11:30 PM.  This was also the rainiest day of a dry July.

 

The following six days had hot temperatures and more than two inches of rain (ranked in descending chronological order):

• Aug. 14, 2005 - High/Low of 96/72.  After the high temperature was reached around 1:30 PM three thunderstorms between 2PM and midnight dumped 3.10" of rain.  The storm between 6-7PM produced 1.70" (with nearly an inch falling in a 20-minute period) while the third storm dumped 0.83" between 9-10PM.  Dew points were in the low to mid-70s and the heat index rose to 104° in the early afternoon.

• Aug. 8, 2007 - This hot, wet day was different from the others in that torrential rain fell at dawn.  2.50" poured down between 4:00 and 6AM, flooding (and shutting down large portions of the subway system).  And a tornado touched down in Brooklyn.  After a low of 73° the temperature rose to 90° in the afternoon.

 

 

• July 21 , 1983 - High/Low of 95/69.  The 2.26" of rain that fell in the evening became known as the 'Diana Ross Thunderstorm' because it forced Ross to stop her free concert in Central Park when a severe storm bore down shortly after her performance began.  The rain fell heavily for three hours, from 5:30 until 8:30.

• Aug. 26 1941 - On a day that had a high/low of 93/68, 2.30" of rain fell, most of it between 5:15 and 7PM.  The day before 1.83" of rain in the early afternoon, but the high was only 75°.

• July 1, 1933 - After a high of 94°, a heat index in the low 100s and dew points in the low 70s, 2.16" of rain poured down between 7:25 (when the temperature was 88°) and 9:45 PM.

• June 27, 1932 - High/Low of 90/72.  Much of the day's 2.11" of rain fell between 7:00 and 9PM, but there was also a quick downpour between 4:00 and 5PM.  During the first half of the afternoon the dew point was in the mid-70s.  

 

And here are other days with highs mostly in the mid-to-upper 90s along with significant rainfall:

• July 25, 2016 - High/Low of 93/73 and an inch of rain, which fell from 2:45 until 5:45 PM. During the thunderstorms the dew point rose to 77°
• July 7, 2012 - High/Low of 97/72 and 0.50" of rain.  The rain fell during a late thunderstorm between 10 PM and midnight.
• July 18, 2006 - High/Low of 95/71 and 0.69" of rain.  Most of the rain was measured between 9-10 PM.
• Aug. 2, 2002 - High/Low of 97/70 and 0.70" of rain.  0.42" poured down in a 15-minute period between 7:15 and 7:30 PM.
• July 8, 1994 - High/Low of 94/73 and 0.82" inches of rain.  Much of the rain (0.70") fell from a thunderstorm between 2-3 PM.
• Aug. 28, 1993 - High/Low of 95/71 and 0.53" of rain.  All of the rain fell in an hour between 4-5PM.
• July 23, 1991 - High/Low of 99/72 and 0.53" of rain.  A thunderstorm between 4:30 and 6 PM brought all of the rain.
• July 17, 1988 - High/Low of 94/71 and 1.21" of rain.  A strong thunderstorm dumped an inch of rain in an hour between 5:30 and 6:30 PM.  Earlier in the day there had also been showers in the wee hours of the morning.
• July 1, 1971 - High/Low of 94/73 and 1.56" of rain.  Thunderstorms moved in after 2 PM, with much of the rain falling from two storms between 2-3:00 (0.42") and 5-6:00 (0.65"). 
• July 18, 1969 - High/Low of 94/77 and 0.88" of rain.  All of the rain poured down in the hour between 3-4 PM.
• Aug. 7, 1955 - High/Low of 93/73 and 0.97" of rain.  The rain fell from a mid-afternoon thunderstorm between 2-3 PM and a nighttime thunderstorm between 8:30-11 PM.
• July 28, 1949 - High/Low of 97/77 and 1.10" of rain.  (No hourly information is available for this month.)
• Aug 16, 1944 - High/Low of 96/73 and 0.88" of rain.  The rain fell between 4:30-7:40 PM.  This was the seventh day in a row with a high of 95° or hotter (and tomorrow would be the eighth).
• July 11, 1940 - High/Low of 92/67 and 1.94" of rain. (No hourly information is available for this month.)
• July 7, 1934 - High/Low of 97/74 and 0.83" of rain.  Rain fell during two thunderstorms between 7-8PM and 11-midnight.  Before the storms moved in the humidity was around 45% range but then jumped above 90% once the clouds opened up.
• July 28, 1931 - High/Low of 97/78 and 0.26" of rain.  The heat index was around 100°, and just before a mid-afternoon thunderstorm moved in it was in the low 100s as the humidity rose from 40% to 80%.  The rain fell in a short period of time, between 3:05 and 3:40 PM.
• July 13, 1916 - High/Low of 94/70 and 0.97" of rain.  Two thunderstorms produced the rain, between 3:00 and 4 PM and 5:00-8 PM.  Shortly before the storms moved in the dew point was an incredibly uncomfortable 80° and heat index at 2PM was a wicked 112°.

 

For an entire summer, the hottest and wettest summer is that of 1991.  It was the 12th hottest and had 15.86" of rain (average amount is 12.50").  Second is the summer of 1983 which was fifth hottest and had 13.48" of rain.  Other warm and wet summers include 2011, 2006 and 1984.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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July 2015 Weather Recap: A Very Warm Second Half

 

 

• Although July 2015 was warmer than average (+2.2 degrees), three of the Julys since 2010 were hotter.  Overall it was the 19th hottest July since 1900.  Only six days were cooler than average.  After being close to average during the first two-and-a-half weeks of the month, temperatures from July 19-31 were nearly five degrees above average.

• The number of 90-degree days was five, which is below the average number of eight.  However, eight days had highs of 88° or 89°, which tied July 1994 for the greatest number of upper-80s highs (going back to 1970).

• All but two days had highs of 80 or warmer (an average July has six days with highs below 80).  Since 1970 only three Julys have had more 80-degree days (2011, 1994 and 1983). 

• It appeared the month was going to be the driest July since 2002, but then 1.95" of rain poured down during the afternoon of 7/30, which was as much rain as fell in the previous four weeks.  This was the greatest daily rainfall since 1/18, when 2.10" fell.  It was also the first rain to fall on 7/30 in fifteen years.

• The month's hottest temperature was 96° on 7/29; the warmest low was 82° on 7/20.  At the other end of the temperature spectrum, July's coolest reading was 64° on 7/16; the coolest high was 75° on 7/4. 

• Finally, although July 2015 and 2012 had the same mean temperature, their diurnal variations (i.e., the difference between high and low) were very different, with 2015's being 14.2 degrees and 2012's at 17.0.  Although this year's average high was 1.4 degrees cooler than July 2012, the average low was 1.4 degrees warmer.

 

JULY TEMPERATURE AVERAGES SINCE 2010
	Average			Degrees	Highs of
	High	Low	Mean	+/-	90+	88/89
2015	85.9	71.7	78.8	+2.3	5	8
2014	83.5	68.8	76.1	-0.4	3	3
2013	86.3	73.4	79.8	+3.3	10	3
2012	87.3	70.3	78.8	+2.3	10	6
2011	88.9	71.6	80.2	+3.7	14	3
2010	90.1	72.6	81.4	+4.9	20	5

 

 

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