........we were wondering when the next below average month was going to happen, they had become that seldom events. Infact by 1st August 2005, the last month that was below the 1971-2000 average was July 2004, a year before. 

If we compare the period 1st January 2001 to 1st August 2005 to the period 1st January 2011 to 1st August 2015 with the number of months that were below the 1971-2000 average, it is quite revealing

1st Jan 01-1st Aug 05: 11

1st Jan 11-1st Aug 15: 24

If we compare last decade, 2000-09 with the current one 2010 to present day and the number of months that were at least 0.5C below the 1961-90 average.

Months at least 0.5C below the 1961-90 average since January 2000

Aug 2014: 14.9
Jun 2013: 13.6
May 2013: 10.4
Mar 2013: 2.7
Feb 2013: 3.2
Oct 2012: 9.7
Sep 2012: 13.0
Jul 2012: 15.5
Jun 2012: 13.5
Apr 2012: 7.2
July 2011: 15.2
Dec 2010: -0.7
Nov 2010: 5.2
Aug 2010: 15.3
May 2010: 10.7
Feb 2010: 2.8
Jan 2010: 1.4
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Dec 2009: 3.1
Jan 2009: 3.0
Dec 2008: 3.5
Oct 2008: 9.7
July 2007: 15.2
Mar 2006: 4.9
Oct 2003: 9.2
Oct 2002: 10.1
Dec 2001: 3.6
Mar 2001: 5.2
Jan 2001: 3.2
Jul 2000: 15.5

There were only 12 such months during the 2000s. There have already been 17 such months during the 2010s and we still got over 4 years of this decade left

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The question is why have below average months suddenly increased? I personally think the turning point was the spring of 2008, when the number -NAO months increased from about spring 2008 to January 2011, they were hardly any +ve NAO months in that period. Why did we record so many -ve NAO months? Solar activity? It makes you wonder.

If we compare 1st January 2008 to present day with 1st January 1998 to 31st December 2007 and the number of months below the 1971-2000 average, it is quite stark

1st Jan '98-31st Dec '07: 25

1st Jan '08- present day: 44 and we still got 29 months left before this decadal period is finished.

 

 

 

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My answer fwiw is that we have now moved to a colder period. It definitely feels that way. This decade feels totally different from the 1990s especially the late 1990s.

its feeling a bit more like the 1960s whereby a decent summer was as rare as hens teeth.

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Yes i agree with this although 60s summers were shocking for the most part there wasnt a decent summer between 1959 ( hot and sunny) and 1975 and people think they are hard done by these days . Its odd tho when people of my generation who were kids in the 60s say things like summers are not what they were in my childhood and yet overall summers have improved a lot in the past 20 years , so shows we only remember the sunny hot days of the past which in the 60s were few and far between!

Summers are definitely cooler in the 2010s than the mid 90s to mid 00s period - but one could argue that the frequency of warm summers was higher than normal then. From 1994 to 2006, only 1998 was below average I think. I was thinking 2000 as well but that had disappointing July sandwiched between a good June and August.

 

The 1980s weren't very good, nor the 1960s. Some really shocking summer months in the late 80s - August 1987 springs to mind! If we get anything half as cool as that, this forum would be in meltdown mode.

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Great analysis Kevin.

I suggest declining solar activity as the cause of the increase in below average temperature months in the UK. The 1989 to mid-noughties period coincided with the high activity solar cycles 22 & 23 and we were very fortunate to enjoy the predominantly good summers from 1989 to 2006. The long and strong solar minimum of 2006 to 2011 with its high number of spotless days certainly reset the synoptic patterns in the UK to much more variability than which prevailed from 1989 to 2006 when zonal winters and anticyclonic spring/summers were favoured.

http://solarscience.msfc.nasa.gov/images/Cycle22Cycle23Cycle24big.gif 

The Lockwood et al paper claimed a link between colder winters and low solar activity but your data shows that it is not just winter months that have become colder.

http://news.bbc.co.uk/1/hi/8615789.stm 

As we are now heading for the next solar minimum, I predict further UK cooling ahead which would be a continuation of the trend clearly shown by the CET.

http://www.metoffice.gov.uk/hadobs/hadcet/graphs/HadCET_graph_ylybars_uptodate.gif 

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The Lockwood paper attributes the link as an increased likelihood of blocking in winter over Europe. The mechanism is that during high solar activity, higher levels of UV from the sun heat the stratosphere. But in the northern hemisphere winter, there is no sunshine in the Arctic so no extra heating occurs here but extra heating does occur in the tropics. This enhances the temperature contrast between the equator and the north pole in the stratosphere which gives the polar Jetstream in the troposphere in winter a boost which makes blocking less likely. In low solar activity, there is less of a temperature contrast in the stratosphere between the tropics and the north pole and this means the polar Jetstream is less energetic and more likely to meander which allows blocking over Europe. Lockwood et al argue that Europe is particularly prone to blocking. The BBC article I link to says that Lockwood was looking into any effects in summer too. I think the effect is not just confined to winter but that synoptics all year round can be affected.

As to effects on global temperature, this is a different topic and best avoided. It is entirely valid to confine the discussion to the UK or Europe as a whole.

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It would be interesting to compare this record over two decades with that of Western Russia and the Baltic States. It certainly feels as if there is a seesaw between the two regions.

For example this summer has been relatively average over there but searingly hot in Western Europe (well... Everywhere except the UK and Ireland).

FWIW I sense the pattern has changed again since 2013 and we are into a more Westerly regime which may possibly be connected with the newly positive PDO - the last two winters have been much more early 2000s-esque. This summer in the UK feels like a bit of an aberration to do more with our proximity to that cold SST region in the Atlantic than the macro pattern.

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The more westerly winters of 2013/14 & 2014/15 might be due to the peak of solar cycle 24 but this has passed now. The zonality of 2013/14 was a special case with the static pattern over North America withcold air persistently discharging over the central plains. Winter 2014/15 did not seem mild and zonal in East Kilbride with 23 days of snow lying between mid Jan & 9 Feb.

So for me, I don't think the pattern has changed recently, but the low sunspot peak did perhaps favour the record warmth across Europe in 2014. I expect low solar activity to favour cold synoptics across Europe from now on although winter 2015/16 with a likely strong nino and positive QBO may well turn out to be zonal.

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I did a bit of number crunching to check whether my suspicions about the NW/SW divide were correct, and want to share the results with you. They are pretty clear.

Running from 1971 to 2014 (the period I use for my E&W summer index) I looked at mean temperature, sunshine and rainfall for the JJA season in 2 regions of the UK as defined by the Met Office: 1. NW England and North Wales, 2. SE and Central Southern England. I then calculated the difference between them for each year and charted how it evolved over time. I'd love to share the charts but my work computer doesn't let me post self-made urls.

Temperature: Ranges from 1.3C in 1977 to 2.6C in 1994, but the difference grows approximately 0.2C over the 40-year period.

Rainfall: Ranges from -27mm in 1991 to -215.3mm in 2009 (the latter borne out by anecdotal evidence), and the mean gap increasing by 45mm in the period!

Sunshine: Ranges from -56.8hrs (NW sunnier than SE!) in 1977 to +200.9hrs in 1994, and the trend is again as clear as a bell: an increasing mean gap of c.40 hours.


So, since 1971 the South and South East have got markedly sunnier, drier and warmer than the North West and N Wales. It's what we all suspected, but to be honest I was surprised by how consistent and clear the trend was. I suspect if we compared with places on the near continent we would see an even stronger trend.

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Looking at Kevin's findings a different way to get the same result,  if the 12 month rolling CET (each month) is plotted against the time period from 2000 to 2015 you get the top graph below.

In comparison to the Global Temperature anomaly from the Met Office using HADCRUT4 data on the lower graph, the two trend lines are going in opposite directions. The CET is showing a trend-line drop of about 0.5C over this 15 year period whilst global temperatures have increased by about 0.05C over the same period

The assumption must be that the regional circulation has changed and influenced the average weather in the UK, presumably driven by jet stream or SST changes over this period

 

 

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Months below the 1971-2000 average since January 2001

JANUARY

Jan 2013: 3.5 (-0.7)
Jan 2011: 3.7 (-0.5)
Jan 2010: 1.4 (-2.8)
Jan 2009: 3.0 [-1.2]
Jan 2001: 3.2 (-1.0)

FEBRUARY

Feb 2015: 4.0 (-0.2)
Feb 2013: 3.2 (-1.0)
Feb 2012: 3.8 (-0.4)
Feb 2010: 2.8 (-1.4)
Feb 2009: 4.1 [-0.1]
Feb 2006: 3.7 (-0.5)
Feb 2003: 3.9 (-0.3)

MARCH

Mar 2013: 2.7 (-3.6)
Mar 2010: 6.1 (-0.2)
Mar 2008: 6.1 (-0.2)
Mar 2006: 4.9 (-1.4)
Mar 2001: 5.2 (-1.1)

APRIL

Apr 2013: 7.5 (-0.6)
Apr 2012: 7.2 (-0.9)
Apr 2008: 7.9 (-0.2)
Apr 2001: 7.7 (-0.4)

MAY

May 2015: 10.8 (-0.5)
May 2013: 10.4 (-0.9)
May 2010: 10.7 (-0.6)

JUNE

Jun 2015: 14.0 (-0.1)
Jun 2013: 13.6 (-0.5)
Jun 2012: 13.5 (-0.6)
Jun 2011: 13.8 (-0.3)
Jun 2008: 13.9 (-0.2)

JULY

Jul 2015: 15.9 (-0.6)
Jul 2012: 15.5 (-1.0)
Jul 2011: 15.2 (-1.3)
Jul 2009: 16.1 (-0.4)
Jul 2008: 16.2 (-0.3)
Jul 2007: 15.2 (-1.3)
Jul 2004: 15.8 (-0.7)
Jul 2002: 16.0 (-0.5)

AUGUST

Aug 2015: 15.9 (-0.3)
Aug 2014: 14.9 (-1.3)
Aug 2011: 15.4 (-0.8)
Aug 2010: 15.3 (-0.9)
Aug 2007: 15.4 (-0.8)
Aug 2006: 16.1 (-0.1)

SEPTEMBER

Sep 2012: 13.0 (-0.7)
Sep 2008: 13.5 (-0.2)
Sep 2001: 13.4 (-0.3)

OCTOBER

Oct 2012: 9.7 (-0.7)
Oct 2010: 10.3 (-0.1)
Oct 2008: 9.7 (-0.7)
Oct 2003: 9.2 (-1.2)
Oct 2002: 10.1 (-0.3)

NOVEMBER

Nov 2013: 6.2 (-0.7)
Nov 2012: 6.8 (-0.1)
Nov 2010: 5.2 (-1.7)
Nov 2005: 6.2 (-0.7)

DECEMBER

Dec 2012: 4.8 (-0.3)
Dec 2010: -0.7 (-5.8)
Dec 2009: 3.1 (-2.0)
Dec 2008: 3.5 (-1.6)
Dec 2007: 4.9 (-0.2)
Dec 2005: 4.4 (-0.7)
Dec 2003: 4.8 (-0.3)
Dec 2001: 3.6 (-1.5)

Notable how few below average Mays and Septembers there have been, May 2010 was the first below average May since 1996 

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Thanks Kevin,great set of stats there

The interesting stand out I noticed is the sheer number,8,below average Julys and Decembers we`ve had Especially from 2007 to date!!

We are definatly in a period of colder winters and cooler summers,2014 being the exception.

We still have not recorded an April that was at least 1.0C below the 1971-2000 average since the average came into existence. We still haven't even recorded an April that was at least 1.0C below the 1961-90 average when that average came into existence and that was 25 years ago. 

An indication on the absence of cold Aprils in the last 25 years. You got to feel that we are long overdue a really cold April.

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It'd be interesting to see how many of those vanish from the list if 1981-2010 averages are used! There are a heck of a lot of -0.1, -0.2 and -0.3s on there...

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Aren't most of the 1981-2010 averages higher than the 1971-2000 ones? I think there is only December that isn't.

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