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The Warmest September ever recorded?


West is Best

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Posted
  • Location: Derbyshire Peak District. 290 mts a.s.l.
  • Weather Preferences: Anything extreme
  • Location: Derbyshire Peak District. 290 mts a.s.l.
There is no strong correlation between a warm September and a mild winter. 3 of the warmest 10 Septembers in the last 100 years preceded mild winters (1998, 1949, 1947), 3 preceded cold winters (1961, 1958, 1933) and 4 preceded average or near-average winters (2005, 1999, 1959, 1929). As is often the case, these hypotheses about certain conditions in certain months leading to certain conditions in following months are exposed for what they are...baloney.

In general, Nick, I agree with your final sentence. My post above was more to highlight a statistical quirk rather than offer a very warm September as a forecasting tool for the winter ahead.

I differ on your choice of cold winters following a warm September. Both 1961 and 1958 fell into my category of 'one cold month, the rest of the winter mild or around average', 1933 did not feature at all as the September mean was 14.9c and I used 15.0c as a lower limit.

1780 was the last truly cold winter to follow a 15.0c+ September and 226 years is a very long time, hence my tongue in cheek closing sentence.

T.M

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Posted
  • Location: Irlam
  • Location: Irlam
Winters 1958-59 and 1961-62 were only slightly below average, not that cold really.

Overall they were not that cold, however they did contain notable cold spells, for instance the second half of December 1961 was sub zero CETwise and January 1959 was a cold month, colder than any month since February 1991 with a CET of 1.6

Here's that list again, I've posted it on here twice of Septembers with a CET of 15.0 and greater and the following winter

September

2005 15.2 Winter CET: 4.1

1999 15.6 Winter CET: 5.4

1961 15.2 Winter CET: 3.6

1958 15.1 Winter CET: 3.6

1949 16.3 Winter CET: 5.1

1929 15.3 Winter CET: 4.6

1898 15.2 Winter CET: 5.8

1865 16.3 Winter CET: 5.3

1825 15.1 Winter CET: 3.8

1795 16.0 Winter CET: 6.2

1780 15.6 Winter CET: 3.4

1779 15.2 Winter CET: 1.4

1760 15.7 Winter CET: 5.8

1750 15.2 Winter CET: 3.2

1731 15.3 Winter CET: 4.7

1730 15.3 Winter CET: 2.5

1729 16.6 Winter CET: 4.6

1708 15.0 Winter CET: 1.2

1678 15.0 Winter CET: 1.0

Winters with CET <2: 3

Winters with CET between 2 and 3: 1

Winters with CET between 3 and 4: 5

Winters with CET between 4 and 5: 4

Winters with CET between 5 and 6: 5

Winters with CET >6: 1

So there's 9 winters with a CET of less than 4C and 10 winters with a CET of greater than 4C

So does a September with a CET>15C lead to a mild winter?

Well it depends from which year you are observing from, in recent times you would say it lead to a mild winter but pre 1760 you could say it favoured a cold winter

Inconclusive, I would say

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Nick's post was most likely taken from Philip Eden's Saturday Telegraph article which I read earlier. Some very good points although I agree that winter 1999/2000 was more accurately defined as a mild winter. December was quite snowy in parts of Scotland with frequent polar maritime north-westerlies, but January was almost completely snowless, and February likewise barring a brief NW'ly on the 16th with snow for some. Temperature wise, December was cold in Scotland and average elsewhere; Jan and Feb were mild everywhere.

From a scan of past synoptic charts, 1961/62 looks like it was a fairly snowy winter despite not being all that cold; Dec 1961 had potent NW'lys early in the month and some more cold weather at the end, and Feb 1962 had a potent looking easterly near the end.

1958/59 is interesting; December appeared to be uneventful, January was dominated by northerlies, and February was anticyclonic. Not sure how snowy the January was away from the usual favoured parts of Scotland and NE England in northerly situations, but it would appear to have been exceptionally sunny.

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Posted
  • Location: Skirlaugh, East Yorkshire
  • Location: Skirlaugh, East Yorkshire
I would suggest that when final figures come in or at the end of the year the September CET could possibly get revised down to 16.7 or 16.6. They first put June down as 16.1 and then downgraded it to 15.9.

This simply isnt true. At the time when the June CET was published there were arguments on this forum on whether the Manley (16.1°C) or the Hadley value (15.9°C) were the correct to use. The argument was with regards to whether the month was the equal warmest since 1976 along with 2003.

There hasnt been any changes made to the Hadley CET values since 2004.

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Posted
  • Location: Powys Mid Wales borders.
  • Location: Powys Mid Wales borders.
Here's that list again, I've posted it on here twice of Septembers with a CET of 15.0 and greater and the following winter

So does a September with a CET>15C lead to a mild winter?

Well it depends from which year you are observing from, in recent times you would say it lead to a mild winter but pre 1760 you could say it favoured a cold winter

Inconclusive, I would say

Dejavour springs to mind here:lol:

50:50 I`d say overall :)

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Posted
  • Location: Putney, SW London. A miserable 14m asl....but nevertheless the lucky recipient of c 20cm of snow in 12 hours 1-2 Feb 2009!
  • Location: Putney, SW London. A miserable 14m asl....but nevertheless the lucky recipient of c 20cm of snow in 12 hours 1-2 Feb 2009!
all we need now is a few more winters with more or less absence of frost and we'll be well on our way to producing great wine and having the south covered in mediterranean flora.

has anyone else noticed that olive trees now seem to be hardy in the Southern England climate and are now even beginning to be planted as street trees in parts of central london (no, this is not a joke - i couldn't believe my eyes when i saw this the other week).

Both grapevines and olives are much hardier than is generally supposed - they certainly don't need frost-free conditions, especially when planted in well-drained, stony soil. Both - but especially olives - can come a cropper where they have to over-winter in heavy, waterlogged ground; and I don't think an olive would much appreciate a succession of windy, well sub-zero days either (fat chance, nowadays :) !).

Both, however, need a long, warm summer to ripen their fruit; and that is where the warming British climate has already improved things massively for the grape, and may well enable decent olive crops in the future.

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Posted
  • Location: Shrewsbury
  • Location: Shrewsbury
Both grapevines and olives are much hardier than is generally supposed - they certainly don't need frost-free conditions, especially when planted in well-drained, stony soil. Both - but especially olives - can come a cropper where they have to over-winter in heavy, waterlogged ground; and I don't think an olive would much appreciate a succession of windy, well sub-zero days either (fat chance, nowadays :) !).

Both, however, need a long, warm summer to ripen their fruit; and that is where the warming British climate has already improved things massively for the grape, and may well enable decent olive crops in the future.

I think the main reason Mediterranean plants struggle in Britain is that the Mediterranean climate isn't just about warmth but sunshine and rainfall as well. What you don't get in the Med in summer is long stretches of mainly overcast weather, or drizzly days, or "sunshine and showers"- it's quite easy for a Mediterranean city to manage 50mm+ monthly rainfall in August but you can almost guarantee it'll be from one or two large but brief thunderstorms, with the ground drying in a few hours. Particularly the sunshine- how many summer months in the last few years have been warm but dull?

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Posted
  • Location: Brixton, South London
  • Location: Brixton, South London
I think the main reason Mediterranean plants struggle in Britain is that the Mediterranean climate isn't just about warmth but sunshine and rainfall as well. What you don't get in the Med in summer is long stretches of mainly overcast weather, or drizzly days, or "sunshine and showers"- it's quite easy for a Mediterranean city to manage 50mm+ monthly rainfall in August but you can almost guarantee it'll be from one or two large but brief thunderstorms, with the ground drying in a few hours. Particularly the sunshine- how many summer months in the last few years have been warm but dull?

Substantially agree with you both:

1. Drainage is crucial: grapes grown for wine (as opposed to dessert grapes) mostly prefer sloping "poor" soil (e.g. gravel beds in the Medoc, slaty soils in the Mosel/Saar, chalk in Champagne and the sony soil of Chateauneuf du Pape in the southern Rhone [interestingly some of the Syrah grown in Cote Rotie in the northern Rhone (the "Cote Brune") are grown on clay soil albeit on very steep terraced hillsides].

2. Grapes are remarkably hardy and can certainly survive temperatures of -20c in winter: the killer is mid/late spring frost as in 1956 in Bordeaux.

3. For the so-called "noble" grape varieties the crucial months for ripening are August and September (even October where growers delay picking because of a cool wet summer as in 1978 in Bordeaux). Traditionally these 2 months caused problems for British wine growers although the recent trend towards drier warmer Augusts and Septembers in south east England has undoubtedly helped the quality, image and range of English wines in recent years. Sunshine as well as warmth is essential: warm damp conditiond encourage mould/rot etc.

4. I rather doubt that cold dry winter winds are harmful to either grapes or olives: consider the mistral in the Rhone valley!

5. Points 1, 2 and 4 would apply to many Mediteranean shrubs/trees: the killer being water-logged clay soil in winter (I speak from the bitter experience of seeing my French Lavender ("Lavender Stoechas") die from water logging in poorly prepared London clay...).

Regards

ACB

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Posted
  • Location: Steeton, W Yorks, 270m ASL
  • Location: Steeton, W Yorks, 270m ASL
I think the main reason Mediterranean plants struggle in Britain is that the Mediterranean climate isn't just about warmth but sunshine and rainfall as well. What you don't get in the Med in summer is long stretches of mainly overcast weather, or drizzly days, or "sunshine and showers"- it's quite easy for a Mediterranean city to manage 50mm+ monthly rainfall in August but you can almost guarantee it'll be from one or two large but brief thunderstorms, with the ground drying in a few hours. Particularly the sunshine- how many summer months in the last few years have been warm but dull?

I'm sure there are more knowledgeable botanists out there with far more than my layman's understanding, but I'm fairly sure that the general restriction to poleward migration of plants is the presence of sustained cold, and the ability of perennials to wintstand frost. Tropical species thrive in year round warmth and high humidity; many mediterranean species have a hardiness to cope not with cold, but summer drought. I suspect the barrier to migration has been more temperature than rainfall therefore. Arid plants may not thrive in our more humid conditions, but I'm fairly sure it wouldn't kill them; cold winters would.

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Posted
  • Location: Manchester
  • Location: Manchester

I don't think sunshine, sustained warmth or long, warm summers have much to do with the survival of exotic plants in the UK. It's pretty much completely down to frost. Look at New Zealand for example- all kinds of palms are able to grow there and the summers are mostly cooler than the UK. I'd say that sunshine is probably lower too. The lack of frost is what enables them to survive, regardless of the levels of sunshine or summer heat.

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Posted
  • Location: Bognor Regis West Sussex
  • Location: Bognor Regis West Sussex
I'm sure there are more knowledgeable botanists out there with far more than my layman's understanding, but I'm fairly sure that the general restriction to poleward migration of plants is the presence of sustained cold, and the ability of perennials to wintstand frost. Tropical species thrive in year round warmth and high humidity; many mediterranean species have a hardiness to cope not with cold, but summer drought. I suspect the barrier to migration has been more temperature than rainfall therefore. Arid plants may not thrive in our more humid conditions, but I'm fairly sure it wouldn't kill them; cold winters would.

I had a grape vine in the garden for years but finally cut it down as every year it suffered from mould, however I reckon this was more to do with the soil (brick earth) than humidity. On the south downs they flourish and Sussex vineyards produce some lovely wines as do vineyards in the Dorking area and in other Surrey vineyards. Certainly September has been an outstanding month with the sea temp still very warm down here, I was paddling a few days ago. However even today in a supposedly cooler spell the temp has been 17.6C and a lot of people are still wearing T shirts, me included so perhaps October will be warm too.

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