The 100 Hottest (CET) Days

[Roger J Smith]

The Hundred Hottest Days (CET 1772-2019)

Ranking the hottest days in the daily CET records for mean daily temperatures ... July 2019 values are now final.

Rank __ Mean __ Date(s)

_t1 ____ 25.2 ___ 29 Jul 1948, 25 Jul 2019

_ 3 ____ 24.9 ___ 1 Aug 1995

_ 4 ____ 24.7 ___ 4 Jul 1976

_t5 ____ 24.6 ___ 3 Jul 1976, 2 Aug 1995, 19 Jul 2006, 1 Jul 2015

_ 9 ____ 24.5 ___ 13 Jul 1808

t10 ____ 24.4 ___ 14 Jul 1808, 3 Aug 1990

t12 ____ 24.0 ___ 5 Jul 1852, 13 Jul 1923

t14 ____ 23.9 ___ 24 Jul 1818, 5 Jul 1976, 2 Aug 1990, 9 Aug 2003

t18 ____ 23.7 ___ 15 Jul 1825, 12 Jul 1923, 28 Jul 1948, 8 Aug 1975

_22____ 23.6 ___ 13 Aug 1911

t23 ____ 23.5 ___ 19 Jul 1825, 20 Jul 2016 

t25 ____ 23.4 ___ 29 Jul 1911, 31 Jul 1943, 4 Aug 1975, 31 Jul 1995, 3 Aug 1995

t30 ____ 23.3 ___ 18 Jul 1825, 6 Jul 1976 

t32 ____ 23.2 ___ 22 Jul 1868, 9 Aug 1911, 26 Jul 2006

t35 ____ 23.1 ___ 6 Jul 1852, 21 Jul 1868, 30 Jul 1948, 22 Jul 1989, 5 Aug 2003, 24 Jul 2019

t41 ____ 23.0 ___ 28 Aug 1942, 3 June 1947, 29 Jul 2001, 19 Jul 2016 

t45 ____ 22.9 ___ 15 June 1858, 20 Jul 1878, 1 Jul 1976

t48 ____ 22.8 ___ 27 June 1826, 27 Aug 1930, 19 Aug 1932, 7 Aug 1975, 2 Jul 1976

t53 ____ 22.7 ___ 21 June 1817, 27 June 1878, 13 Jul 1983, 21 Jul 1989, 16 Jul 2003, 2 Jul 2006, 20 Jul 2006, 25 Jul 2006, 1 Aug 2013

t62 ____ 22.6 ___ 11 Jul 1783, 18 Aug 1893, 19 Jul 1901, 2 Sep 1906, 7 Jul 1923, 29 Aug 1930, 28 Jun 1976, 7 Jul 1976,

_________________ 12 Jul 1983, 11 Aug 1997, 15 Jul 2003 

t73 ____ 22.5 ___ 10 Aug 1773, 30 Jul 1830, 14 Jul 1847, 5 Aug 1868, 11 Aug 1884, 12 Jul 1941, 6 June 1950, 1 July 1952, 

_________________ 27 June 1976, 14 Jul 1983, 10 Aug 1997, 6 Aug 2003, 1 Jul 2009, 27 Jul 2018, 23 Jul 2019

t88 ____ 22.4 ___ 12 Jul 1808, 17 Aug 1876,  21 Jul 1911, 11 Jul 1923, 28 Aug 1930, 5 Sep 1949, 29 June 1976, 13 Jul 1983

_________________ 23 Jul 1989, 10 Aug 2003 

t98 ____ 22.3 ___ 17 Jul 1834, 22 Jul 1869, 18 Jul 1921, 22 Jul 1925, 22 June 1941, 2 June 1947, 6 Jul 1957, 26 June 1976

_______________________________________________________

 

[Rob K]

Surprised that yesterday didn't rank higher. The extent of the 35C+ temperatures across the country was amazing.

[Quicksilver1989]

1 hour ago, Rob K said:

Surprised that yesterday didn't rank higher. The extent of the 35C+ temperatures across the country was amazing.

I think the CET is based on stations in Central-Western England if I recall, perhaps temperatures in western areas away from the main heat dragged it down a tad.

[DAVID SNOW]

The station in the NW was well below the other 2.

[Roger J Smith]

I have edited the value posted now for yesterday, it was 24.7 C, tied third warmest. We'll see where that stands at the final adjustment at month's end.

[Roger J Smith]

The top 100 list is actually 105 due to the ties for 98th place 22.3 C.

So of those 105, this is how they break down by 30-year intervals (the first one is missing its first year). A random distribution would average 12 in these 30-year intervals and 4 in the current decade.

1772-1800 _ 2 _________ 1921-1950 _ 21

1801-1830 _10 _________1951-1980 _16

1831-1860 _ 5 _________ 1981-2010 _ 28

1861-1890 _ 8 _________ 2011-2019 _ 8

1891-1920 _ 7 _________

Only about 20% of the years contributed days to this top 105 list. 

 

 

 

[Madshenry45]

This was insightful.

[Roger J Smith]

One other stat of interest, the 105 hottest days span the period 2 June to 5 September which is 96 days, but of those only 58 provide at least one (the record max for the other 38 falls below 22.3). The dates most frequently represented in the list (with four) are 1st, 12th, 13th and 22nd of July. The longest stretch of days with multiple cases is 18-25 July, then 29 July to 3 August. There are no dates missing from the 11th of July to the 11th of August. Only 13 cases fall 2nd to 20th of June or 13th August and later. 

The top 39 (23.1 and higher) all fall between 1st July and 13th August. For the entire set of 105 days, the dates included are as follows (each asterisk represents an additional day). 

12 in June _ 2 3 6 15 21 22 26 27** 28 29

64 in July _ 1*** 2* 3 4 5* 6** 7* 11* 12*** 13*** 14** 15* 16 17 18* 19*** 20** 21** 22*** 23* 24* 25* 26 27 28 29** 30* 31*

27 in August _1* 2* 3* 4 5* 6 7 8 9* 10** 11* 13 17 18 19 27 28* 29

 2 in Sept __ 2, 5

 

 

[Roger J Smith]

Meanwhile, here's an additional list of all other hot days 22.0 to 22.2 that didn't make the top 100 and ties ... there are 48 additional days in this addition, for a total of 153. Any 21.9 days would be tied 154th. 

t106th _ 22.2 __ 16 July 1793, 2 Aug 1856, 18 July 1859, 16 July 1868, 5 Aug 1897, 18 and 20 July, 1901, 12 Aug 1911,

__________ 19 July 1921, 4 Aug 1933, 26 July 2018

t117th _ 22.1 __ 5 July 1836, 15 Aug 1893, 10 July 1921, 14 July 1926, 21 June 1941, 18 Aug 1947, 22 and 23 Aug 1955,

__________ 5 Aug 1975, 30 June 1976, 12 July 1983, 24 July 1989, 19 Aug 1995, 19 Aug 1996,19 Aug 1997, 19 June 2005, 18 July 2006.

t134th _ 22.0 __ 15 July 1779, 16 July 1808, 1 Aug 1825, 22 June 1846, 13 July 1847, 25 July 1872, 17 Aug 1893,

__________ 20 July 1900, 15 & 16 July 1912,  5 & 6 Aug 1933, 24 June 1935, 17 Aug 1947, 12 Aug 1953, 3 Aug 1975,

__________ 11 Aug 1995, 8 Aug 1997, 11 July 2005, 27 June 2011

t154th _ 21.9 

Oddly enough, this lower threshhold does not extend the season, anything before 2 June or after 5 September is below 22.0 C. It does add eight days in the 96-day interval to reach 66 days with at least one representative. August gains proportionately more than July in this extended version. 

____________________________________________________________________________________

The following is the complete list of dates filled by the 153 hottest days (extending the table from the previous version). 

__ * for each additional hot day. 

18 in June _ 2 3 6 15 19 21* 22* 24 26 27*** 28 29 30  

85 in July _ 1*** 2*3 4 5** 6**7*10 11**12****13****14***15***16****17 18**** 19****20****21** 22*** 23* 24** 25** 26* 27 28 29**30*31*

48 in August _1**2** 3**4* 5****6*7 8*9* 10** 11**12*13 15 17** 18* 19*** 22 23 27 28* 29

 2 in Sept __ 2, 5

[Roger J Smith]

Also, this is the expanded frequency count for the 30-year periods for all 153 of the days that reached a mean of 22.0 or higher. 

At random, the 30-year intervals should have about 18 hot days and the recent decade (most of nine summers) should have 6.

The years 1975 and 1976 account for 17 alone.  

 

1772-1800 _ 4 _________ 1921-1950 _ 30

1801-1830 _12 _________1951-1980 _ 22

1831-1860 _10 _________ 1981-2010 _ 39

1861-1890 _10 _________ 2011-2019 _ 10

1891-1920 _16 _________