Exceptionally above average months 1971-2000

[Summer of 95]

Here are the number of times the named months have been 2C or more above the 1971-2000 average, since 1971 (source:http://www.personal.dundee.ac.uk/~taharley/centralengav_temperat.htm)

Jan: 4

Feb: 6

Mar: 2

Apr: 1

May: 1

Jun: 2

Jul: 4

Aug: 4

Sep: 1

Oct: 4 (3 of them since 2001)

Nov: 1

Dec: 2

There certainly seems to be a trend whereby it's the "high summer" (Jul-Aug) and "midwinter" (Jan-Feb) months that have the greatest tendency to be exceptionally above average, very recently joined by October due to the extraordinary spate of 13C+Octobers since 2001.

I was inspired to do write this by reading the April CET thread, and thinking how rare it seems to be to get an April as far above average as so many Jans, Febs, Julys and Augusts manage- people were going for 10C plus but even though many Aprils are warmer than average I've noticed how seldom it really surges past the 2C above mark (10.1): only the memorable April of 1987 which I remember well has managed it in 36 years. Only one more has just made it to +1.5C; the equally memorable 2003.

Similarly May; I often think that although it should be a warm dry sunny month, it rarely seems to produce something really exceptional; again it's the only May I remember as really good (1992) that makes it.

Why is this I wonder? The only thing I can suggest is the greater variability in the spring (and to some extent autumn) months; when hot sunny days are frequently followed by cold nights, and when it can suddenly change from very hot for the time of year to very cold (eg May 1995)- cancelling each other out.

[Thundery wintry showers]

It probably does have a lot to do with variability; in winter it's quite common to have long spells of SW winds, and in summer it's quite common to have long spells of anticyclonic heat, neither of which tend to persist for long in spring.

I also suspect that it's hard to find synoptic setups that are conducive to prolonged exceptional heat in spring; anticyclonic/southerly regimes are probably the only way, and such regimes rarely persist even at other times of the year. A cyclonic/south-westerly type tends to result in suppressed maxima, while a generally anticyclonic May tends to have maxima 2-3C above average, but minima less than 1C above.

[summer blizzard]

I think it is due to the fact that Spring is the most anticyclonic season on paper, this means that minima generally has a greater chance of being lower, even if maxima is high, this month is a good example, an outurn barely 1C above average yet high maxima.

[Lettucing Gutted]

this month is a good example, an outurn barely 1C above average yet high maxima.

July 1996, August 1996, July 1997, October 1999, December 1999, July 2005, August 2005 February 2003 September 2003, December 2003, December 2005 are other examples of months that have high maxima being countered by low minima thus resulting in 'mild' rather than 'very warm' overall C.E.Ts. A lot of the Mays since 1992 have had mild overall C.E.Ts instead of exceptionally warm C.E.Ts with the exception of Mays 1998 and 1999.

[North-Easterly Blast]

It is unusual about October in that although since and including 2001 we have had three Octobers with CETs of 13.0 or greater, and even Oct 1995 recorded 12.9, there was a run of average Octobers from 1997-2000 and indeed a run of average to cool Octobers from 2002-2004. So, although there have been four exceptionally above average Octobers in the past 12 years, and also Oct 1996 was pretty warm (11.7), the other seven were certainly not what you would call warm Octobers.

September is what strikes the biggest warming trend for me. Although Sep 2006 was the warmest on record, and Sept 1999 almost made the exceptionally above average category (15.6, +1.9), four other Septs in the last 10 years were certainly in the warm category (14.9, 14.7, 14.9, 15.2). Since 1996 apart from Sept 2001 which was average to even very slightly below (13.4) there has not been any other September which has recorded anything close to average for the CET.

Also, we have not had a below average May since 1996, and the only average May in the last 11 years was in 2005.

The last 12 months have also been truly exceptional. Four of the last 12 months have been exceptionally above average (July, Sep, Oct 2006, Jan 2007), also June 2006 and Feb 2007 were certainly well above average. It is sickening to see that we have not had a below average month since March 2006, and not even a close to average month since last August.

[Thundery wintry showers]

Yes, Septembers and Mays have been remarkably "above average" in recent years.

I tend to think of 1998 as being the start of the warm Mays; May 1997 was a notably varied month and was also the last May to feature widespread snowfall across the British Isles, with a CET only a few tenths of a degree above the 1961-90 average. Strangely, September 1997 was also not especially warm up here in the North East, owing entirely to cool nights, but it does appear to have been a warm month in most other regions.

[J10]

Yes, Septembers and Mays have been remarkably "above average" in recent years.

I tend to think of 1998 as being the start of the warm Mays; May 1997 was a notably varied month and was also the last May to feature widespread snowfall across the British Isles, with a CET only a few tenths of a degree above the 1961-90 average. Strangely, September 1997 was also not especially warm up here in the North East, owing entirely to cool nights, but it does appear to have been a warm month in most other regions.

I think September 2007 will live long in the memory of many and that week's long warm sunny weather seems to remain at the forefront.

[Weather-history]

It is unusual about October in that although since and including 2001 we have had three Octobers with CETs of 13.0 or greater, and even Oct 1995 recorded 12.9, there was a run of average Octobers from 1997-2000 and indeed a run of average to cool Octobers from 2002-2004. So, although there have been four exceptionally above average Octobers in the past 12 years, and also Oct 1996 was pretty warm (11.7), the other seven were certainly not what you would call warm Octobers.

The one thing to really note about October is there has been a notably warming trend in that month overall since the 1940s. There have been 150 Octobers with a CET of 10 or over and 48 of them have occurred since and including 1940. So about a third of that total of 150 has occurred in the last 66 years. There has been only 9 sub 10C Octobers in the last 40 years. So where sub 10C Octobers were the majority in the past, are now very much in the minority.

[North-Easterly Blast]

Studying long term trends, until 1988 there was no sign of any warming trend in the British Climate very much above what was experienced over the past three centuries. The warming process kicked in abruptly in January, February and March in the late 1980s, and a notable warming process kicked in for September around 1997. November joined the bandwagon of the warming trend around 1994, although there was a run of mild Novs in the early 1980s. May also joined the warming bandwagon around 1998. It does now look possible and quite likely that June also joined the bandwagon in 2003. July and August are less easy to pin down as to when they joined the warming trend, but there has been a general easing up since the late 1980s.

All the above mentioned months have joined the warming bandwagon around 1988 or more recently, but December joined the warming trend earlier, around the early 1970s. After the unusually cold December decade of the 1960s had passed, there began a run of mild Decembers around the start of the 70s and this generally persisted through the 1970s and 1980s followed by a slight easing back since then. But you are right Kevin B, and I can certainly identify that October was the first month to ever join the warming trend, and this happened as early as the late 1950s. Before then sub 10*C Octobers occurred more often than half the time, and even 11+ Octobers were relatively rare; ever since the end of the 1950s sub 10*C Octobers have been the exception and not the norm like they were in the pre 1950 era.

[Summer of 95]

Studying long term trends, until 1988 there was no sign of any warming trend in the British Climate very much above what was experienced over the past three centuries. The warming process kicked in abruptly in January, February and March in the late 1980s, and a notable warming process kicked in for September around 1997. November joined the bandwagon of the warming trend around 1994, although there was a run of mild Novs in the early 1980s. May also joined the warming bandwagon around 1998. It does now look possible and quite likely that June also joined the bandwagon in 2003. July and August are less easy to pin down as to when they joined the warming trend, but there has been a general easing up since the late 1980s.

All the above mentioned months have joined the warming bandwagon around 1988 or more recently, but December joined the warming trend earlier, around the early 1970s. After the unusually cold December decade of the 1960s had passed, there began a run of mild Decembers around the start of the 70s and this generally persisted through the 1970s and 1980s followed by a slight easing back since then. But you are right Kevin B, and I can certainly identify that October was the first month to ever join the warming trend, and this happened as early as the late 1950s. Before then sub 10*C Octobers occurred more often than half the time, and even 11+ Octobers were relatively rare; ever since the end of the 1950s sub 10*C Octobers have been the exception and not the norm like they were in the pre 1950 era.

The bandwagon is certainly a good way to think of it. I'd concur that different months joined it at different times: the late 80s certainly for Jan and Feb, late 90s for May and September I'd agree. June certainly seems to have leapt aboard in the last few years, but I think we'll have to wait till about 2010 before we can be sure of its fare-paying passenger status; given the memories of those awful 1990s Junes. December interestingly to me seemed to get on about 1970, then jump off around 1990 at the same time Jan and Feb jumped on; perhaps 2006 was the start of a renewed ride? March also about 1988, but hasn't held on quite as tightly as Jan or Feb in some years (1995-6 2001, 2006).

The comment about October having joined in the 1950s is interesting; however the one month that has not been pinned down is April. To me, it either jumped on first of all- in the early 1940s which started an extroardinary run of warm Aprils, or, given what seems like a lot of 10C+ Aprils in the second half of the 18th century in particular, and the fact that after the 1940s warming there was a long spell from 1961-1987 without a very warm April, and there have been relatively few since, April is the only month that has yet to jump on?

[Weather-history]

The comment about October having joined in the 1950s is interesting; however the one month that has not been pinned down is April. To me, it either jumped on first of all- in the early 1940s which started an extroardinary run of warm Aprils, or, given what seems like a lot of 10C+ Aprils in the second half of the 18th century in particular, and the fact that after the 1940s warming there was a long spell from 1961-1987 without a very warm April, and there have been relatively few since, April is the only month that has yet to jump on?

The Aprils of the 1790s were very peculiar alternating between the warm and cold

1790: 6.1

1791: 9.6

1792: 10.0

1793: 6.2

1794: 10.2

1795: 7.7

1796: 10.2

1797: 7.4

1798: 10.4

1799: 5.4

Another interesting period is the lack of cool Junes between 1771 and 1791 inclusive. Only 3 were below 14C and the lowest was 13.6, 7 were 15.0C or over From June 1768 to June 1813, there was a single June that was below 13C

Also the Junes of 1824-1846 inclusive, there were just 3 below 14C and 10 that were 15.0C or over.

Another thing to note is from June 1929 to 1970, there wasn't one June that was below 13C in that 41 year period but there have been 6 in the last 36 years

Edited April 2, 2007 by Mr_Data

[Summer of 95]

The Aprils of the 1790s were very peculiar alternating between the warm and cold

1790: 6.1

1791: 9.6

1792: 10.0

1793: 6.2

1794: 10.2

1795: 7.7

1796: 10.2

1797: 7.4

1798: 10.4

1799: 5.4

Another interesting period is the lack of cool Junes between 1771 and 1791 inclusive. Only 3 were below 14C and the lowest was 13.6, 7 were 15.0C or over From June 1768 to June 1813, there was a single June that was below 13C

Also the Junes of 1824-1846 inclusive, there were just 3 below 14C and 10 that were 15.0C or over.

Another thing to note is from June 1929 to 1970, there wasn't one June that was below 13C in that 41 year period but there have been 6 in the last 36 years

1790s look like an exciting decade:

1790 March colder than Feb, April colder than either!

1791 Warm April, cold December

1792 Warm April, May only just warmer, at 16.9 August warm for that era

1793 Very cold April, hot July but cool August, warm October

1794 Amazing year. Jan cold, Feb very mild, March colder than Feb, April very warm. June (15.7) and July (18.1) would be considered hot today let alone 200 years ago. Then another big July-August deterioration, a la 1994 and 2006. December fairly cold in preparation for the big winter

1795 Jan coldest ever, Feb and Mar also very cold. But looks like a very hot September (16.0, none hotter between 1949-2006)

1796 really strange, very mild winter with March its coldest month. Warm April and May only just warmer. Subzero December.

1797 Cold April and spring in general, Warm July (17.3)

1798 Warm April, June (16.9) surely one of the hottest ever? June warmest month of the year but all 3 summer months over 16C which is rare even these days. Cold December

1799 Really cold-looking year: no subzero months but no less than 6 months below 6C (in other words colder than any month of this last winter).

[Thundery wintry showers]

I think April is looking like a month that is warming erratically, rather than undergoing a marked step-change. This is also suggested by the snow amounts, which have been declining erratically rather than showing a step-change (such as in May, when therre were fairly widespread snow events in 1993, 1995, 1996 and 1997, but nothing of note since). The trend is certainly upward although the height of the 1940s is yet to be reached. October is similar; I think it has warmed erratically over the past 100 years or so, with a blip upwards around the 1960s.

The change around June 2003 was certainly a step change; I have a feeling that it will mark the time when June jumps on the bandwagon, but only time will tell on that one.

[Lettucing Gutted]

I think April is looking like a month that is warming erratically, rather than undergoing a marked step-change. This is also suggested by the snow amounts, which have been declining erratically rather than showing a step-change (such as in May, when there were fairly widespread snow events in 1993, 1995, 1996 and 1997, but nothing of note since). The trend is certainly upward although the height of the 1940s is yet to be reached.

I think April joined the "bandwagon" again in 2002. At 9.3C April 2002 was a degree above the 1960-1990 average of 8.0C and the 1971-2000 average of 8.1C. April 2002 was also nearly 2 degrees above its predecessor - April 2001 which had a C.E.T of 7.7C.

Also with the coming Southeasterly heatwave April 2007 could secure April's "seat on the bandwagon" especially if April 2007 returns a C.E.T of 10.C or more.

[SP1986]

I think April joined the "bandwagon" again in 2002. At 9.3C April 2002 was a degree above the 1960-1990 average of 8.0C and the 1971-2000 average of 8.1C. April 2002 was also nearly 2 degrees above its predecessor - April 2001 which had a C.E.T of 7.7C.

Also with the coming Southeasterly heatwave April 2007 could secure April's "seat on the bandwagon" especially if April 2007 returns a C.E.T of 10.C or more.

I very much doubt April will be as warm as people suggest. I think one cooler trend could take it hurtling down to about 8.8-9°C or something of that order, although still above average

[Weather-history]

Since this thread was posted, April 2007, January 2008, April 2009 and very likely February 2011 have been added to the listed.

The last occasions of a month being 2.0+ above the 1971-2000 average

January: 2008

February: 2011

March: 1997

April: 2009

May: 2008

June: 2003

July: 2006

August: 2003

September: 2006

October: 2006

November: 1994

December: 1988

[damianslaw]

Since this thread was posted, April 2007, January 2008, April 2009 and very likely February 2011 have been added to the listed.

The last occasions of a month being 2.0+ above the 1971-2000 average

January: 2008

February: 2011

March: 1997

April: 2009

May: 2008

June: 2003

July: 2006

August: 2003

September: 2006

October: 2006

November: 1994

December: 1988

Notable how long it has been relatively speaking since we have had a particularly very mild November and December. However, I suspect Nov 97 and 06 were not far off being above 2 degrees alongside Dec 94, 97, 04.

February is very telling, it seems to have a propensity to being particularly mild in some years when heights stay strong over France and we are left in southwesterlies, yet it is the winter month when traditionally see the atlantic at its quietest and when easterly regimes are most likely to take hold. We have had one or two cold Febs in the last 20 years i.e. 1991, 1996 but most Febs have seen short lived cold spells quickly replaced by very mild weather such as happened in Feb 09, last Feb saw sustained chilly weather but nothing severe.

Of all the winter months Feb has teased us and played around with us the most, Jan has in the main mostly dissapointed for cold and snow, and Dec I now class as the best winter month on average in the past 20 years, yes there have been some shockers for mild and wet i.e. 1994, 1997 spring to mind but most have delivered at least some cold weather and in some cases snowy weather of both varying intensity and duration as shown below:

snowy easterly spells a la 1995, 1996, 2001, 2005, 2008, 2009, 2010

cold anticyclonic weather i.e. 1992,2002, 2006, 2007

polar maritime airstreams 1993, 1999, 2003, 2004 (short lived)

cold northerlies 1998, 2000.

The only really dissapointing ones for snow have been 1994, 1997 and in the south 2004.

1991 didn't fit in any category though there was a cold anticyclonic spell mid month.

and away from the north 2004.

Edited February 27, 2011 by damianslaw

[Summer of 95]

I'd totally, completely forgotten starting this thread, but I see I did it on the eve of that amazing April 2007 which blew away so many records. Very surprised that April 2009 made the list, as it never topped 18C here despite not having and cold weather. 2003, 1997 and 1987 were all better Aprils for warm spells.

Not November 2002? Constant southwesterlies, almost no frost, 10C+ virtually every day, and very dull as well- I'd have put money on that one being in there. Nov 2009 wasn't much better.

[virtualsphere]

Thought it would be an interesting idea to work out the reverse - i.e. months 2C or more below the 1971 - 2000 average.

Not sure if I've done this right so please do point out any errors:

January: 2010 (before this,1987)

February: 1991

March: 1987

April: 1986

May: 1996

June: 1991

July: 1965 (this can't be right?! Came close in 1988)

August: 1986

September: 1986

October: 1992

November: 1993

December: 2010 (and before this 2009, then 1996)

This illustrates well that we are overdue a cold summer, and also a very cold March and April.