4 week anomalous periods split over 2 months

[damianslaw]

As we look to record one of the sunniest and warmest April's on record. It got me thinking how many times have we seen equally anomalous 4 week spells of either cold, heat, rain or no rain that have coincided with half of two calendar months and therefore dont register in the record books, must be plenty that would eclipse whole complete calendar month recordings. Sometimes anomalous spells coincide with complete calendar months sometimes not. For example the cold of second half dec 2009 first half Jan 2010, 4 week period must have returned a mean close to freezing, yet the dec and Jan themselves ended up appreciably above hence no reference. 

[Weather-history]

Mid January-mid February 1917 was something like -1.3C for CET

January  1917: 1.6 
February 1917: 0.9

 

 

[damianslaw]

13 hours ago, Weather-history said:

Mid January-mid February 1917 was something like -1.3C for CET

January  1917: 1.6 
February 1917: 0.9

 

 

That's a very good example, what did the Jan and Feb themselves return?

[Weather-history]

On 28/04/2020 at 20:51, damianslaw said:

That's a very good example, what did the Jan and Feb themselves return?

I've posted it   

[B87]

June 2005 probably a good example.

[sundog]

Would mid dec 81 - mid Jan 82 be one such period.  Although dec was below average overall I think Jan came in around average . 

I guess though thats more of a 6 week period, dec up to mid Jan.

Edited May 3, 2020 by sundog

[damianslaw]

35 minutes ago, sundog said:

Would mid dec 81 - mid Jan 82 be one such period.  Although dec was below average overall I think Jan came in around average . 

I guess though thats more of a 6 week period, dec up to mid Jan.

If you took a mid month to mid month period not far off, though the cold set in around 8 dec so it was 5-6 week duration. Mid dec 96 to mid Jan 97 good example take 4 weeks from 14 dec to 11 Jan. 

[Weather-history]

Mid June-mid July 2004: 14.2

June 2004: 15.3

July 2004: 15.8

 

 

[Roger J Smith]

I now have a table in my excel file showing 31-day averages ending on every day in the daily data. So from that, here is a summary of the warmest "months" without reference to a calendar (except I give the dates so I guess there is a reference). To make this a bit easier to follow, I have lumped together all periods that had a maximum in the same year as the more recognizable calendar month extremes. For the 30-day months and for February more so, these will look a bit "off" because the averages must include one to three days from some other month. In every case though, the recognized monthly champs win out for a time. So the "recognized" years are in red and the outliers which spanned more like mid-month to mid-month intervals are in regular type colour. 

I could do the same for cold periods except that a lot of contenders are from before daily data began. But I may get into that for whatever we can glean. 

This table starts with the 31 day interval 25 Dec to 24 Jan (the first one shared by 1915-16) and works down to the interval 24 Dec to 23 Dec (which is 1975-76). There are some ties, a second decimal tie-breaker is used, losing case in italics. A tie preserved to second decimal has (t) beside the value. Because there were two brief rivals for 1915-16 that lasted just a couple of days each, I show those first, with the date values staggered to align with the longer series from 1915-16. The second of these rivals picks up the challenge towards the end of the Jan 1916 reign and finally manages one day of supremacy (6 Jan to 5 Feb). The value for 23 Dec 1915 to 22 Jan 1916 also tied as mentioned near the end of the list (but rounded up, the rival there was almost 0.1 warmer but rounded down to 7.4). The value for 24 Dec 1915 to 23 Jan 1916 was 0.1 short of its rival for that interval.

Leap year day isn't much of a factor because no candidates emerged from leap years over the span of February-March. 

Quite a few years have had their monthly credentials lost due to what you might call the "tyranny of the calendar." There were for example 17 consecutive intervals where 2002 would have been a warmest month (running mid-Jan to mid-Feb) compared to the 13 for the recognized January champ 1916. If 31-day months started on 13th or 14th Jan we would be talking about the 8.0 month in 2002. 1976 (summer) and 2005 (autumn) are other months that do as well as or better than most "calendar month" champs. And there are a surprisingly large number of smaller players which snagged a day or two here and there. 

Values in bold type in the table are the recognized warmest calendar months (if 31 days) and the two values that take one day from an adjacent month for the 30-day months. February 1779 is highlighted for the interval that starts on 31 Jan to 2 Mar which was equal to 1 Feb to 3 Mar and the monthly mark of 7.9. 

Below the table I list a few notable 31-day intervals that did not achieve top rank for their dates (in case you were looking for them).

 

WARMEST 31-DAY INTERVALS

Year(s) ___ First of series _____ Last of series _____ Values (chronological order)

(1920-)1921 _ 25 Dec-24 Jan __ 26 Dec-25 Jan ___ 7.5, 7.5 (t)

(1833-)1834 _ 28 Dec-27 Jan __ 06 Jan-05 Feb _______________ 7.5, 7.6 _____________________7.1, 7.1

(1915-)1916 _ 25 Dec-24 Jan __ 06 Jan-05 Feb ___ 7.5, 7.5 (t),7.5,7.5,7.6, 7.7, 7.6, 7.5, 7.3, 7.3, 7.2, 7.1, 7.1

1846 ___ 06 Jan-05 Feb ______ 07 Jan-06 Feb ___ 7.1, 7.1 (t)

1990 ___ 07 Jan-06 Feb __________________________7.1 (t)

2002 ___ 08 Jan-07 Feb ______ 24 Jan-23 Feb ___ 7.1,7.2,7.4,7,6, 7.8,8.0,8.0,7.9, 7.9,7.8,7.7,7.8, 7.8,7.8,7.6,7.6, 7.5

1869 ___ 25 Jan-24 Feb ______ 28 Jan-27 Feb ___ 7.5, 7.6, 7.8, 7.7

1779 ___ 29 Jan-28 Feb ______ 08 Feb-10 Mar ___ 7.7, 7.8, 7.9, 7.9, 7.9, 8.1, 8.2, 8.2, 8.2, 8.1, 7.9

1998*___ 08 Feb-10 Mar ______ 10 Feb-12 Mar ___ 7.9, 7.9, 7.9

1961 ___ 11 Feb-13 Mar ______ 15 Feb -17 Mar ___ 7.9, 7.9, 8.0 , -- , 8.1

2019 ___ 12 Feb-14 Mar ______ 15 Feb-17 Mar _______ 7.9, 8.0, 8.1, 8.1  (aligned with 2 above)

1990 ___ 16 Feb-18 Mar ______ 23 Feb-25 Mar ___ 8.3, 8.5, 8.6, 8.7, 8.7, 8.6, 8.5, 8.5

1957 ___ 23 Feb-25 Mar ______11 Mar-10 Apr ____ 8.5,8.7,8.8,8.9, 9.0,9.1,9.2,9.3, 9.3,9.4.9.6,9.9, 9.9,9.8,9.7,9.6, 9.5

2017 ___ 11 Mar-10 Apr ______ 12 Mar-11 Apr ____ 9.5, 9.4

1999 ___ 13 Mar-12 Apr ______ 14 Mar-13 Apr ____ 9.5, 9.4

1815 ___ 14 Mar-13 Apr __________________________ 9.4

1945 ___ 14 Mar-13 Apr ______ 22 Mar-21 Apr ___ 9.4 (9.5) 9.9,10.2,10.3,10.6,10.8,11.0,11.0 10.9, (10.8, 10.7 10.6 as this spell fell behind 2011).

2011 ___ 14 Mar-13 Apr ______ 1 Apr - 1 May ____ 9.4,9.6,(9.8,10.1),10.3,(10.3,10.3,10.5,10.8) 10.9,11.1,11.2,11.3,11.4,11.5,11.5,11.7,11.8,11.8

_____ (cont'd until 14 Apr - 14 May) ____________ 11.8,11.6,11.6,11.8,11.9,12.0,12.1,12.1,12.2,12.2,12.2,12.2,12.3

2007 ___ 10 Apr-10 May _____________________ 12.2

1775 ___ 13 Apr-13 May _____ 14 Apr-14 May ___ 12.2, 12.3

1893 ___ 15 Apr-15 May _____ 20 Apr-20 May ___ 12.5, 12,7, 12.8, 13.0, 13.1, 13.1

1833 ___ 21 Apr-21 May _____ 6 May-5 June ____ 13.3,13.6,13.8,14.0, 14.2,14.5,14.5,14.6,  14.7,14.9,15.1,15.3, 15.5,15.4,15.4,15.3

_____ (cont'd until 12 May-11 June) ____________ 15.4,15.5,15.5,15.6,  15.7,15.7

1992 ___ 13 May-12 Jun _____________________ 15.6

1822 ___ 14 May-13 Jun ____ 17 May-16 Jun ____ 15.7, 15.9, 16.1, 16.2

1846 ___ 18 May-17 Jun ____ 3 Jun-3 Jul _______ 16.2,16.5,16.8,17.2,  17.4,17.7,17.7,17.7,  17.7,17.8,17.8,18.0,  18.1,18.1,18.1,18.1,  18.1^

1976 ___ 4 Jun - 4 Jul ______ 27 Jun-27 Jul _____ 18.3, 18.6, 18.9, 19.1, 19.2, 19.2, 19.1, 19.3, 19.5, 19.6, 19.6, 19.7, 19.7, 19.8, 

_________________________________________ 19.9, 20.0, 20.1, 20.2, 20.2, 20.1, 20.0, 19.9, 19.7, 19.6

2006 ___ 28 Jun-28 Jul ____ 3 Jul - 2 Aug _______ 19.5, 19.7, 19.7, 19.7, 19.6, 19.4

1983 ___ 3 Jul -2 Aug ________________________ 19.4 

1995 ___ 4 Jul- 3 Aug _____ 2 Aug-1 Sep _____ 19.4, 19.7, 19.7, 19.7, 19.7, 19.6, 19.5, 19.4, 19.4, 19.5, 19.5, 19.5, 19.6, 19.7, 19.8, 19.9

_____ (cont'd) ____________ (20 Jul-19 Aug)__ 19.9, 19.9, 20.0, 20.2, 20.3, 20.2, 20.2, 20.1 (note warmest 31-d int 24 Jul to 23 Aug 1995 = 20.3)

_____ (cont'd) ____________ (28 Jul-27 Aug) __ 20.0, 19.8, 19.6, 19.4, 19.2, 18.9 (t) ___ 

1997 ____ 2 Aug-1 Sep _____ 8 Aug-7 Sep ____ 18.9 (t), 18.8, 18.9, 18.8, 18.7, 18.5, 18.3  

1947 ____ 8 Aug-7 Sep ____ 18 Aug-17 Sep ___ 18.3, 18.4, 18.3, 18.3, 18.4, 18.3, 18.2, 18.0, 18.0, 17.9, 17.6

1780 ____ 19 Aug-18 Sep __________________ 17.4

1949 ____ 19 Aug-18 Sep ___ 25 Aug-24 Sep ___ 17.4, 17.3, 17.1 (16.9, 16.8 not rec) 16.8, 16.7 (t)

1947 ____ 21 Aug-20 Sep ___________________ 17.1

2016 ____ 21 Aug-20 Sep ___ 23 Aug-22 Sep ___ 17.1, 17.1, 17.0

2006 ____ 25 Aug-24 Sep ___13 Sep-13 Oct ___ 16.7(t),16.8,16.7,16.7, 16.8,16.9,16.8,16.8, 16.7,16.5,16.3,16.1, 16.0,15.7,15.7,15.8, 15.8,15.7,15.5,15.3

1949 ____ 7 Sep - 7 Oct ____________________15.7 (this period generally ran 0.2 to 0.4 lower than above, managed the one tie here, then went ahead ...)

1949 ____13 Sep-13 Oct ___ 24 Sep-24 Oct ____ 15.3, 15.2, 15.2, 15.2, 15.1, 15.0, 14.9, 14.8. 14.6, 14.4, 14.2, 13.9

2006 ____21 Sep-21 Oct ___ 24 Sep-24 Oct ________________________________________ 14.6 _________ 13.9

2011 ____ 24 Sep-24 Oct ___ 25 Sep-25 Oct ____ 13.9, 13.9

2001 ____ 26 Sep-26 Oct ___3 Oct-2 Nov ______  13.8, 13.8, 13.7, 13.5, 13.5, 13.3, 13.1, 13.1

2005 ____ 2 Oct-1 Nov ____17 Oct-16 Nov ______ 13.1, 13.1, 13.2, 13.1, 13.0, 13.0, 12.8, 12.7, 12.7, 12.5, 12.4, 12.1, 11.9, 11.7, 11.5, 11.2

2015 ____ 17 Oct-16 Nov __ 22 Oct-21 Nov ______ 11.2, 11.2, 11.2, 11.2, 11.1, 10.8

1978 ____ 23 Oct-22 Nov __ 26 Oct-25 Nov ______10.7, 10.8, 10.7, 10.4

1994 ____ 26 Oct-25 Nov __18 Nov-18 Dec ______ 10.4,10.5,10.6,10.5, 10.4,10.2,10.0,9.9, 10.0 9.9,9.8,9.6, 9.6,9.5,9.4,9.3, 9.3,9.4,9.5,9.2,8.9,8.6,8.6,8.5

1828 ____ 19 Nov-19 Dec __ 21 Nov-21 Dec ______ 8.5, 8.6, 8.6

2015(-16) _19 Nov-19 Dec __14 Dec-13 Jan _______ 8.5,(8.5),8.6,8.9, 9.1,9.3,9.4,9.4, 9.5,9.5,9.6,9.7, 9.7, 9.5,9.4,9.2,9.2, 9.1,8.9,8.8, 8.6,8.5,8.4,8.4,8.3,8.2

1974-75 __ 15 Dec-14 Jan __ 22 Dec-21 Jan ______ 8.2, 8.2, 8.2, 8.1, 8.0, 7.9, 7.7, 7.6

1975-76 __ 22 Dec-21 Jan __ 24 Dec-23 Jan ______ 7.6, 7.6, 7.6

(1915-16) _ 23 Dec-22 Jan ________________________ 7.6 ___ (then resumes top of this table) ... 

 

________________________________________________

2007 ... the warmest 31-day interval associated with Jan 2007 was 7.3 (23 Dec 2006 to 22 Jan 2007) not a record.

*1998 ... 06 Feb - 08 Mar (8.1) fell short of the 1779 mark by 0.1. This spell did gain some traction after a few more days. 

When 2019 was overtaken by 1990 (16 Feb-18 Mar), it was then running about equal with 2017 for several days. This shows the comparison:

2017 ___ 17 Feb-19 Mar ______ 20 Feb-22 Mar _____________________ 8.1, 8.2, (8.1), 8.1

2019 ___ 12 Feb-14 Mar ______ 23 Feb-25 Mar ____7.9, 8.0, 8.1, 8.1, 8.1, 8.1,(8.1), 8.2, 8.3, 8.3, 8.1, 8.1

1990 ___ 16 Feb-18 Mar ______ 23 Feb-25 Mar __________________ 8.3, 8.5, 8.6, 8.7, 8.7, 8.6, 8.5, 8.5

1947 came very close to matching 1833 for 6 May to 5 June (15.2). 

^1846 peaked at 18.2, 18.3 for next two intervals but was overtaken by 1976 then. 18.2 was also its average for 30-day June. 

2019 came close again for 27 Jun to 27 Jul (19.3) which was a bit behind both 1976 and 2006 which were ending and starting runs respectively.

1868 peaked at 19.1 for the interval 7 July to 6 August. 

1911 had 19.5 for three consecutive intervals (19 Jul-18 Aug to 21 Jul-20 Aug). These lost out to 1995 however. 

1975 and 2003 were both close to 1995 for intervals ending in early August. 1975 had 19.0 for any of five consecutive intervals 13 Jul - 12 Aug to 17 Jul - 16 Aug while 2003 had 19.2 for 13 Jul to 12 Aug and 14 Jul to 13 Aug. These almost caught 1995 during a less impressive portion of its long run. 

The August portion of 1976 never challenged various 31-day maxima, but its highest 31-day average was 17.7 for 3 Aug to 2 Sept. 

==================================================

On the subject of cold 31-day intervals, here are two recent ones that stand out:

-1.5 for the 31-day intervals ending 26 or 27 Dec 2010 (starting 26 or 27 Nov). 

and 0.0 (actually -0.04) for the interval 14 Dec 2009 to 13 Jan 2010. 

The cold March of 2013 was lowered only slightly to a mean of 2.3 for 9th March to 8th April. 

In 2006, the interval 21 Feb to 23 Mar averaged only 3.1 C. 

And back in 1963, the "month" of 26 Dec 1962 to 25 Jan 1963 averaged -2.7 C, even closer than the calendar months to the all-time records (both Jan 1795 and 1814 improve little by any other interval than their calendar months, but an unknown cold month may be this one -- 17 Dec 1860 to 16 Jan 1861 averaged -1.4 C, similar to well-known Jan 1776, 1838 or 1881.

 

[Roger J Smith]

Now for the same analysis of coldest 31-day intervals throughout the year, with the qualifier that more months pre-1772 (before daily data) factor into the coldest month scenarios, so except for where we can compare those over calendar months, this will apply only to years from 1772 to present. 

As in the first table, ties are shown by second decimal, the lesser (in this case warmer) tied value by that measure is in italic script, and if the second decimal does not show a winner, the letter (t) shows an absolute tie. Values in brackets in long series are not records but hold place for the count of days mentioned, shown where a comparison with a rival period is ongoing. The most logical place to start this table is where three rivals (Dec 1962-63, Dec 1813-Jan1814 and Dec 1794-Jan 1795) gear up to dominate the first several weeks of the calendar year. (Jan 1795 -3.1, Jan 1814 -2.9, but 1813-14 has the coldest 31-day interval which ran 27 Dec 1813 to 26 Jan 1814 at -3.24 so that is actually the coldest "month" in the records). Jan 1795 had no colder intervals than the calendar month (-3.1). 1962-63 competes here also and snags a few intervals here and there, picking up five starting 21-25 Dec and then nine more starting from 7 Jan 1963. 1838 joins in starting with 7 Jan-6 Feb but fails to score despite using the coldest day in the series; 1838 did fairly well against 1795 and 1814 but lost out to 1963. The coldest intervals for 1776 and 1881 are also shown, neither manage to score a coldest 31-day interval although improving on their monthly means slightly.

Another three-winter comparison is shown for 1855, 1895 and 1947 starting around mid-January. 1855 fails to set any coldest intervals but keeps very close to its rivals. 1947 eventually overcomes 1895. There are also some intervals from 1917 shown for comparison. 

Values in bold type and blue colour indicate the calendar month extremes (slightly altered for Feb and 30-day months since these are lists of 31-day running means).

Underlined values are also monthly means in comparative cases (as they are comparative they won't be the extreme values there). Jan 1963 obviously is somewhat under-rated as a cold month because it has considerably colder intervals available on either side of the calendar month itself which is a minor peak of temperature.

 

COLDEST 31-DAY INTERVALS

YEAR(S) ___ Duration of cold _______ Values in the period specified (brackets mean not a record, shown for comparison only)

1813-14 ___ 21 Dec-20 Jan to 9 Jan-8 Feb ___(-1.5, -1.7) -2.1 (-2.3) -2.7,-3.0, -3.2, -3.2,-3.2,-3.1,(-2.9, -2.9, -2.8, -2.6) -2.6, -2.6, -2.6, (-2.5, -2.2, -2.0)

1794-95 ___ 21 Dec-20 Jan to 10 Jan-9 Feb __ (-1.7, -1.9,-2.1, -2.4, -2.5,-2.8, -2.9, -2.7, -2.7, -2.9),-3.0, -3.1, -2.9, -2.8, -2.6, (-2.4,-2.4, (-2.4,-2.4, -2.3, -2.2

1962-63 ____21 Dec-20 Jan to 10 Jan-9 Feb _ -1.8, -2.0, -2.3, -2.5,-2.7,(-2.7, -2.7, -2.6, -2.4, -2.2, -2.2, -2.1, -2.1, -2.3, -2.3, -2.4, -2.5), -2.6, -2.5, -2.4. -2.4

_1963_ cont'd 11 Jan-10 Feb to 15 Jan-14 Feb_-2.3, -2.2, -2.0, -1.8, -1.7 (then just higher than 1895, -1.5, -1.5, -1.4, -1.3, -1.2 to 20 Jan-19 Feb).

(compare 1917 same intervals) ____________ (-1.1, -1.1, -1.2, -1.2, -1.2)

(note 1684 and 1740 likely had intervals in ranges -2.5 to -3.5 also)

1838 ______ 07 Jan-06 Feb to 09 Jan-08 Feb ______________________________________________________________________(-2.5, -2.4, -2.1)

(1776 coldest __ 1-6 Jan to 31 Jan and 1-5 Feb ___________________________________________((-1.6))(-1.9, --1.9, -1.9, -1.8, -1.9)

(1881 coldest __ 28 Dec-27 Jan to 3 Jan-2 Feb) ___________________________(-1.6, -1.6, -1.7, -1.6, -1.5. -1.5, -1.6)

(1822-23 quite cold also same intervals as above) __________________________(-1.3, -1.3, -1.2)

_ (records resume here) _

1784 _____ 17 Jan-16 Feb and 18 Jan-17 Feb both -1.2

1963 (from above info) _________________-1.5, -1.5, -1.4, -1.3, -1.2 (continued slow increase for 14 more intervals, last neg was 3 Feb to 5 Mar).

1895 _____ 16 Jan-15 Feb to 30 Jan-1 Mar_ -1.8, -2.0, -2.2, -2.3, -2.4, -2.5, -2.6, -2.6, -2.5, -2.5, -2.4, -2.3. -2.2, (-1.9, -1.7)

1855 _____ 16 Jan-15 Feb to 30 Jan-1 Mar_ (-1.3, -1.6, -1.8, -1.8, -1.9, -2.0, -2.0, -2.2, -2.2, -2.2, -2.0, -1.9. -1.9, -1.7, -1.5 )

1947 _____ 21 Jan-20 Feb to 4 Feb - 6 Mar______________________ (-1.6,-1.7, -1.8, -1.9, -2.1, -2.3) -2.3, -2.2, -2.2, -2.0, -1.9, -1.9, -1.9, -1.9, -2.0

_1947 __ cont'd 5 Feb-7 Mar to 20 Feb-22 Mar _ -2.1, -2.1, -2.0, -1.9, -1.7, -1.7, -1.6, -1.5, -1.4, -1.2, -1.0, -0.7, -0.4, -0.1, (0.3, 0.7) not lowest

___ 1814 not quite equalling 1947 for 16 Feb-18 Mar to 18 Feb-20 Mar then set some_____________________________0.1,  0.0, 0.1,

___ 1845 with coldest mid-March days had 0.4 for 18 Feb - 20 Mar ____________________________________ 0.5, 0.4, 0.5

__ (this ends the subzero CET 31-day intervals until late Nov to late Dec) __ 

1814 ______ 19 Feb-21 Mar to 23 Feb-25 Mar _ 0.2, 0.3, 0.6, 0.9, 1.1

1785 ______ 23 Feb-25 Mar to 9 Mar-8 Apr _(aligned with above)  1.1, 1.2, 1.2, 1.1, 1.0, 1.0, 1.2, 1.4, 1.4, 1.4, 1.5, 1.7, 1.9, 2.0, 2.3

(1674) _____ no daily data but monthly mean _____________________________________ 1.0 

2013 _____ 9 Mar-8 Apr to 10 Mar-9 Apr ____ 2.3, 2.3, (then 2.5, 2.7) not lowest _ 2013 two ties lost on second decimals to 1785 then 1837.

1837 _____ 10 Mar-9 Apr to 2 Apr-2 May ____ 2.3,2.2,2.1 2.1, 2.1,2.1,2.1,2.1, 2.2,2.3,2.4,2.6, 2.8,3.0,3.2,3.5, 3.7,4.0,4.1,4.2, 4.4 4.6,4.9, 5.2

(1701) _____ no daily data but monthly mean equal to 1837 (4.7) __________________________________________________ 4.7 ___

_ (difference is due to 31-day interval not being precisely equal to month)

1782 ____ 2 Apr-2 May to 17 Apr-17 May _____ 5.2, 5.2, 5.2, 5.3, 5.2, 5.3, 5.3, 5.4, (5.6, 5.7), 5.8, 6.0, 6.2, 6.4, 6.7, 6.9 (resumes 22nd) ...

1879 ____ 10 Apr-10 May to 17 Apr-17 May ____ (aligned with above) ___________5.5, 5.6 (5.9, 6.1, 6.4, 6.5), 6.7, 6.9 (t 1855)

1855 ____ 17 Apr-17 May to 22 Apr-22 May ___ 6.9, 6.9, 7.0, 7.2, 7.1, 7.3

1782 ____ 22 Apr-22 May to 1 May-31 May ____ 7.3, 7.3, 7.4, 7.4, 7.4, 7.7, 8.0, 8.4, 8.7, (9.0)

1817 ____ 30 Apr-30 May to 3 May-2 June _____ 8.7, 8.7, 8.9, 9.0

1698, 1740 _ no daily data _____________________8.5/8.6 

1855 ____ 2 May-1 June to 3 May-2 June _____________ 8.9, 9.0

1923 ____ 4 May-3 June to 18 May-17 June ____ 9.0, 8.8, 8.7, 8.7, 8.8, 8.8, 9.0, 9.2, 9.4, 9.6, 9.8 (10.0) 10.1,10.2,10.3

1821 ____ 14 May-13 June to 28 May-27 June __ 9.8, 9.9, 10.1, 10.2, 10.3, 10.4, 10.4,10.5,10.6,10.7,10.8,11.0,11.2,11.4,11.6

1991 ____ 28 May-27 June to 30 May-29 June __ 11.6, 11.7, 11.8

1972 ____ 30 May-29 June to 31 May-30 June _ 11.8, 11.8,

1916 ____ 30 May-29 June to 6 June-6 July ___ 11.8, 11.8 11.8, 11.9, 12.0, 12.1

1909 ____ 30 May-29 June to 3 June-3 July ____(12.0,11.9) 11.8 11.9, 12.0,

1675 ____ no daily data _____ monthly mean (June) __11.5 

1821 ____ 4 June-4 July to 9 June-9 July _____ 12.1, 12.1, 12.1, 12.0, 12.0, 12.1

1907 ____ 10 June-10 July to 19 June-19 July __ 12.2, 12.1, 12.0, 12.0, 12.1, 12.3, 12.4, 12.6, 12.8, 13.0

1980 ____ 19 June-19 July to 22 June-22 July __ 13.0, 13.0, 13.0, 13.1

1879 ____ 22 June-22 July to 29 June-29 July ________________13.1, 13.1, 13.2, 13.2, 13.2, 13.3, 13.3, 13.4 13.5,(13.6)

1802 ____ 29 June-29 July and 30 June-30 July _____________________________________________ 13.4 13.5,(13.5)

1695 ____ no daily data, tied 1802 as second coldest July ______________________________________________ (13.5)

1816 ____ 30 June-30 July to 5 July-4 Aug ___ 13.5, 13.4, 13.5, 13.5, 13.5, 13.5

1841 ____ 6 July-5 Aug to 11 July-10 Aug _____ 13.5, 13.5, 13.5, 13.6, 13.6, 13.6

1812 ____ 11 July-10 Aug to 17 July-16 Aug ___ 13.6, 13.5, 13.5, 13.5, 13.5, 13.5, 13.6

1845 ____ 18 July-17 Aug to 26 July-25 Aug ___ 13.6, 13.5, 13.5, 13.4, 13.2, 13.2, 13.2, 13.3, 13.3 (t)

1912 ____ 26 July-25 Aug to 14 Aug-13 Sep ___ 13.3 It),13,1,13.0,12.8, 12.9,12.9,12.9,12.9, 12.9,12.9,12.9, 12.8,12.8,12.7,12.7, 12.5,12.4,12.3,12.3, 12.3

1986 ____ 14 Aug-13 Sep to 28 Aug-27 Sep ___ 12.3, 12.1, 11.9, 11.8, 11.6, 11.5, 11.3, 11.3, 11.3, 11.2, 11.3, 11.2, 11.2, 11.1, 11.1

1807 ____ 28 Aug-27 Sep to 3 Sep-3 Oct ______ 11.1, 10.9, 10.7, 10.6, 10.5, 10.5, 10.5

1674,1675,1694 ____ no daily data - equal to 1807 for Sept mean __10.5 __________

1952 ____ 3 Sept-3 Oct to 5 Sept-5 Oct ______ 10.5, 10.3, 10.2

1912 ____ 6 Sept-6 Oct  __________________ 10.1

1840 ____ 7 Sept-7 Oct to 17 Sept-17 Oct _____ 9.9, 9.7, 9.4, 9.1, 9.0, 8.8, 8.8, 8.7, 8.6, 8.7, 8.7

1919 ____ 17 Sept-17 Oct to 19 Sept-19 Oct ___ 8.7, 8.5, 8.4 

1817 ____ 19 Sept-19 Oct to 2 Oct-1 Nov _____ 8.4, 8.2, 8.0, 7.7, 7.6, 7.4, 7.2, 6.9, 6.8, 6.6, 6.4, 6.4, 6.4  6.3,

1740 __ no daily data but month was colder than Oct 1817, probably had quite a few cold intervals here 5.3 ... 

1880 ____ 3 Oct -- 2 Nov __________________ 6.4

1896 ____ 4 Oct-3 Nov to 21 Oct-20 Nov _____  6.2, 5.9, 5.8, 5.5, 5.3, 5.0, 4.7, 4.6, 4.6, 4.7, 4.7, 4.6, 4.5, 4.3, 4.1, 4.1, 4.1, 4.1

1786 ____ 21 Oct-20 Nov to 26 Oct-25 Nov ____ 4.1, 4.0, 3.8, 3.7, 3.5, 3.3

1782 ____ 27 Oct-26 Nov to 5 Nov-5 Dec ____ 3.2, 2.9, 2.6, 2.4, 2.4, 2.3, 2.2, 2.0, 1.9, 1.8

1925 ____ 6 Nov-6 Dec to 8 Nov-8 Dec ______1.6, 1.4, 1.4

1879 ____ 9 Nov-9 Dec to 20 Nov-20 Dec ____ 1.3, 1.1, 0.8, 0.6, 0.4, 0.4, 0.6, 0.6, 0.6, 0.4, 0.1, -0.2

2010 ____ 21 Nov-21 Dec to 30 Nov-30 Dec __ -0.4, -0.6, -0.9, -1.1, -1.4, -1.5, -1.5, -1.4, -1.1, -0.9 (-0.7) Dec 2010 mean 2nd to 1890

1796 ____ same dates as 2010, got quite close near end before 1890 had brief run__-0.7,-0.7, -0.5 (-0.3)

1878 ____ also ran a bit less cold than 2010 for these 31d ints _-0.5, -0.8, -0.9, -0.9, -0.8, -0.8, -0.6, (-0.3)

__ (note, 1890 shows non-record values for 25 Nov-25 Dec to 30 Nov-30 Dec)

1890 ____ Dec 1-31 and into Jan 1891 (last entry is 6 Dec - 5 Jan)_(-0.8, -0.9, -0.8, -0.8,-0.7,-0.8), -0.8, -0.9, -1.0, -1.1, -1.2, -1.3

____ (cont'd to include 7 Dec 1890 - 6 Jan 1891 to 13 Dec 1890-12 Jan 1891 _ -1.5, -1.6, -1.7, -1.8, -1.8, -1.9, -1.8, (-1.6, -1.4) not coldest

____ (two more intervals follow for 19, 20 Dec to 18, 19 Jan, listed after the intervening sets below.

1788-89 __ 13 Dec 1788- 12 Jan 1789, to 16 Dec 1788 - 15 Jan 1789 __ (-1.7), -1.7, -1.6, -1.4

1860-61 __ 17, 18 Dec 1860 to 16,17 Jan 1861 averaged -1.4, -1.3 

1890-91 then produced two more extreme intervals for 19, 20 Dec to 18, 19 Jan (-1.5, -1.5). 

This gets the table back to the start of the 1794-95, 1813-14 and 1962-63 cold spells at top of the list. 

====================================================

Here again there are quite a few cases where the calendar does not reveal the full extent of the sets of years with extensive cold spell production. 

While there are twelve coldest months (with some ties added) there are a total of 58 sets of coldest 31-day intervals that could have been calendar months. 

There are a few surprise entries including parts of June-July 1980. 

 

[Weather-history]

On 27/04/2020 at 23:09, damianslaw said:

As we look to record one of the sunniest and warmest April's on record. It got me thinking how many times have we seen equally anomalous 4 week spells of either cold, heat, rain or no rain that have coincided with half of two calendar months and therefore dont register in the record books, must be plenty that would eclipse whole complete calendar month recordings. Sometimes anomalous spells coincide with complete calendar months sometimes not. For example the cold of second half dec 2009 first half Jan 2010, 4 week period must have returned a mean close to freezing, yet the dec and Jan themselves ended up appreciably above hence no reference. 

Last year for our region

July 2019: 107.3

August 2019: 131.3

However mid July-mid August 2019 was around 203mm, so only about 35mm fell during the first half July and second half of August combined.

[damianslaw]

2 hours ago, Weather-history said:

Last year for our region

July 2019: 107.3

August 2019: 131.3

However mid July-mid August 2019 was around 203mm, so only about 35mm fell during the first half July and second half of August combined.

Yes probably more common with rainfall stats. I'm going to start a new thread on rainfall contrasts.

[summer blizzard]

What was the mid-June to Mid-July CET for 2005. 

[Roger J Smith]

6 hours ago, summer blizzard said:

What was the mid-June to Mid-July CET for 2005. 

The peak value was 17.8 which applies to 17 June to 17 July. There was also a boost to mid-August to mid-September with 16.8 reached for 15th August to 14th September. 

[summer blizzard]

2 hours ago, Roger J Smith said:

The peak value was 17.8 which applies to 17 June to 17 July. There was also a boost to mid-August to mid-September with 16.8 reached for 15th August to 14th September. 

Outside 06, 13 and 18 have we seen any other spells beat that since.

[damianslaw]

49 minutes ago, summer blizzard said:

Outside 06, 13 and 18 have we seen any other spells beat that since.

Possibly some points in 2014 and 2016 mid July-mid August maybe?

2005 was preety decent overall. I quite enjoyed it, a bit of rain and cool weather at times, interspersed with decent lengthy spells of warm sunny weather.

Edited May 11, 2020 by damianslaw

[Roger J Smith]

Probably easiest to list the warmest "months" of each year since 1975 (for 31 day intervals). I was thinking of doing this anyway. Some of these intervals may be duplicated for adjacent ranges a day or two apart when rounded to one decimal, but these are based on two decimal values.

WARMEST SUMMER 31-DAY "MONTHS" in RECENT YEARS

Above 17.3 _____________________ Not above 17.3

1975 __ 19.04 __ 16 Jul-15 Aug _____ 1977 __ 15.97 __ 3 Jul - 2 Aug

1976 __ 20.22 __ 22 Jun-22 Jul _____ 1978 __ 15.73 __ 23 Jul - 22 Aug

1982 __ 17.32 __ 7 Jul - 6 Aug ______1979 __ 16.36 __ 4 Jul - 3 Aug

1983 __ 19.51 __ 2 Jul - 1 Aug ______1980 __ 16.82 __ 22 Jul - 21 Aug

1984 __ 17.79 __ 4 Aug - 3 Sep _____ 1981 __ 16.26 __ 10 Aug - 9 Sep

1989*__ 18.25 __ 4 Jul - 3 Aug ______1985 __ 16.17 __ 1 - 31 July

1990 __ 18.63 __ 13 Jul - 12 Aug ____1986 __ 16.65 __ 26 Jun - 26 Jul 

1991^__ 17.39 __ 4 Jul - 3 Aug ______1987 __ 16.07 __ 27 Jun - 27 Jul

1994 __ 18.43 __ 9 Jul - 8 Aug ______ 1988 __ 15.59 __ 20 Jul - 19 Aug

1995 __ 20.31 __ 24 Jul - 23 Aug ____ 1992 __ 16.67 __ 12 Jul - 11 Aug 

1996 __ 17.55 __ 20 Jul - 19 Aug ____ 1993 __ 15.46 __ 22 Jul - 21 Aug 

1997 __ 19.16 __ 25,27 Jul - 24,26 Aug _  1998 __ 16.53 __ 19 Jul - 18 Aug

1999 __ 18.12 __ 7 Jul - 6 Aug ______ 2000 __ 17.09 __ 28 Jul - 27 Aug

2001 __ 17.72 __ 26 Jul - 25 Aug ____ 2007 __ 15.64 __ 12 Jul - 11 Aug

2002 __ 17.52 __ 25 Jul - 24 Aug ____ 2008 __ 16.92 __ 22 Jul - 21 Aug

2003 __ 19.19 __ 13,14 Jul - 12,13 Aug __2009#__17.04 __ 23 Jun - 23 Jul 

2004 __ 18.42 __ 20 Jul - 19 Aug _____2011 __ 15.97 __ 25,26 Jul - 24,25 Aug 

2005 __ 17.79 __ 17 Jun - 17 Jul _____ 2012 __ 17.19 __ 22 Jul - 21 Aug

2006 __ 19.73 __ 30 Jun - 30 Jul _____ 2015 __ 16.70 __ 23 Jun - 23 Jul 

2010 __ 17.37 __ 21,22 Jun - 21,22 Jul __ 2017 __ 17.24 __ 17 Jun - 17 Jul 

2013 __ 19.01 __ 6 Jul - 5 Aug ______

2014 __ 18.09 __10,11 Jul - 9,10 Aug _

2016 __ 17.52 __ 16 Aug -15 Sept ____

2018 __ 19.32 __ 27 Jun - 27 Jul _____

2019 __ 18.22 __ 10 Jul - 9 Aug ______

__________________________________

* 1989 also had 18.23 15 Jul to 14 Aug. The values between these peaks were all above 18. 

^ 1991 equalled max value 17.39 for 23 Jul to 22 Aug. 6 Aug to 5 Sep was 17.36. 

# 2009 had another separate peak of 16.60 for 2 Aug to 1 Sept. There was a 15.6 interval 4 Jul to 3 Aug.