North-Easterly Blast

jules216 From what I know, no strong anomaly either way for the ENSO has ever co-incided with a cold winter as a whole, though in terms of cold weather in the UK, one strong El Nino did co-incide with a cold winter month (Feb 1983), and one strong La Nina did co-incide with the freezing December of 2010, but other than that, not a lot of cold weather has occurred in the UK when the ENSO anomaly has been strong either way.

Bristawl Si September 2010 was not particularly warm; it had a CET of 13.8, which is just above the 1961-90 average but a little below 1991-2020, so I would not be testing the warm September = mild winter theory after a September CET of that level. For anyone looking for comparison of what a high September CET is, the 1991-2020 average is 14.2, and the 1961-90 average is 13.6. I think that a September could be considered warm if it has a CET of 15*C or above, although on the older averages a September CET of 14.5 could be about the breadline. I was meaning to say that it appears to be still possible to have a September CET that is slightly above average (1978, 2009 CET 14.2, 1981, 1985 CETs 14.5 / 14.6), and get a good winter for cold after it, but it appears that warm Septembers in terms of a high CET are bad news from a cold perspective for the following winter.

Bristawl Si After such an exceptionally warm September last year, considering how strong the fact of the UK's weather patterns are that anomalous warmth in September does not favour cold conditions during the following winter, as over the centuries, colder winter weather has been very infrequently seen after a warm September (although it is only clear that warm Septembers have an effect on the following winter, and there is no evidence to suggest that cooler or average Septembers have any bearing on the following winter), I think that winter 2023-24 was already "dead in the water" before it even started. The same was true for other winters in 2021-22 and 2016-17, and further back in 2006-07 and 1999-2000; these winters were already dead in the water before they even started after very warm Septembers. 2023-24 simply joins a list of winters that were ruined by warm September forcing. It clearly appears to be the most predictable aspect of the British Weather, that anomalous warmth in September means that almost if not all the following winter will be mild.

Roger J Smith Thank you for posting this. I knew that this February was very likely to be looking at the warmest first half since 2004 or possibly 2002, but I was not sure about how many other Februarys were as warm as this year by this point or the mid-month point. I think that we are at least likely to be looking at (from January 21st up to this coming February 20th) one of the warmest 31 day CET periods on record in January and February even if we do not quite reach the 8.0 for the period Jan 14th to Feb 13th 2002. I know that the period that you mention in 2002 is the warmest 31 day CET period on record in January and February, and the one that you mention in 1869 at 7.7 is very likely the second warmest, but I am not sure what the other warmest are (say in the top ten).

Weather-history I think that winter 2000-01 is another one of those winters that tries to set up a pattern to deliver a cold winter to the UK, but where the pattern never really comes together in its full potential to deliver the UK a proper cold winter. I think that in 2000-01, Scotland saw frequent cold spells but much of the time England never really saw significant cold for more than short periods - 2000-01 was in many ways like a similar version of 2020-21. In fact I would have thought that winter 2000-01 is a similar solar match to 2023-24 (just before solar maximum) but you are correct that it brought much more in the way of cold outbreaks than 2023-24 has done and now looks to do.

raz.org.rain No, the synoptics of the late 2000s / early 2010s had not occurred for the first time in 50 years. There were excellent examples of northern blocking and northerlies / easterlies in 1978-79, and at times in 1981-82, 1985, 1986, 1987 and to some extent more briefly in the mid 1990s.

damianslaw 2013-14 was just the same as 2019-20. So far winter 2023-24 was a short cold interlude at the start of December, then very mild after the first week of December to the opening days of January - then a benign HP spell, a five day cold outbreak from the north, then very mild again from January 21st until now, and likely until at least next weekend.

Don I hope that next winter we do not see anything as awfully stormy and wet without a sniff of cold like 2019-20 or 2013-14, but even at this early stage, background signals like being close to a solar maximum, a westerly QBO, a possible La Nina do not sound to bode well for cold outbreaks from HLB, developing in the UK during winter 2024-25. Shortly after the last solar minimum, I always thought that winter 2020-21 was the window of opportunity for a cold winter for the UK, and the pattern did try to set up more favourably for cold for the UK, but the pattern never really came together in its full potential for cold, and it did turn cold at times in Scotland, but for the rest of the UK a cold spell was never sustained for more than a small number of days, and was rarely anything especially potent. I always now regard 2020-21 as a "failed cold winter" when the UK missed the opportunity to see a truly cold winter. Another "failed cold winter" further back that I would regard as so further back is 2005-06. That winter had a fair amount of blocking over Scandinavia and eastern Europe, and those areas saw a cold winter that year, but for us in the UK, the really cold air never really made it and the UK was left with often close to average conditions for most of the time. 2005-06 was another so called failed cold winter for the UK, when the opportunity for a cold winter for the UK was there but the pattern never came together in its full potential to get the UK cold.

Don I think that the CET from mid January to mid February 2002 was close to 8*C, which I believe is the warmest monthly period on record straddling two calendar months in January and February. Mid January to mid February this year will not get close to that, due to the cold spell in mid January lasting until the 20th, but this year is still likely to be the warmest mid January to mid February period since 2002. Having said that, the 28 days from January 21st to February 17th this year could record a CET close to or not far off 7.9; which was the overall figure for the warmest February on record in 1779.

One point of note now is that we are very likely to be looking at the warmest first half of February for 20 years (since 2004), and possibly since 2002. Another notable point is that the warmth of this February so far began on January 21st, not at the turn of the month, and the last eleven days of January were overall almost as mild as this month of February has been so far. The mid-January to mid-February period this year must be among the warmest since 2002. Although what happens after next weekend for the remainder of February is still up for grabs, a notable statistic that is now almost a certainty, is that the CET for the 28 day period from January 21st to February 17th this year could get close to the record 7.9 CET for the calendar month of February 1779.

I think that the summer of 100 years previously was much cooler and wetter than 2012.

TheOgre Another notable one to add to your list is July 2006 (hottest on record), followed by July 2007 (wet and cool). I would not call July 2022 to July 2023 as much of an example as Julys 2006 to 2007. February 2022 to February 2023 is not a good example as Feb 2023 was not much cooler than Feb 2022. March 2022 to March 2023 is a good example for rainfall but not significantly cooler for temperature. Another good example is February 1990 (very mild) followed by February 1991 (cold with severe snowy spell in first half). July 1988 (very cool and wet) followed by July 1989 (hot and dry). April 1986 to April 1987 is another good example of the same month the opposite of its preceding partner. Among the most notable of all examples on record that I can think of are August 1911 (hot and dry) to August 1912 (coolest and wettest on record), and January 1795 (coldest on record) to January 1796 (joint 2nd mildest on record).

I think that even though it is a long way off, the earliest background signals for winter 2024-25 are already bad news from a cold perspective for the UK, with a westerly QBO, and being close to solar maximum, and the likelihood of a La Nina. The only thing that it not known at this stage is what September 2024 will be like - if anomalous September warmth will again kill off chances of cold in winter 2024-25.

Derecho If you or anyone says that La Nina winters are front loaded, then apart from 2010-11 and to a lesser extent 2022-23 (the latter was also a weak one), I cannot think of any other clear front loaded La Nina UK winters, though that said in 1999-2000 the February was milder than the earlier part of the winter, although even then the early part of that winter was actually not that cold.

March can have its wintry moments as well - even last year it did turn cold at times during the first half of March, after there had been limited cold in February and even January had not a lot of cold in it either. Having said that, March last year still ended up above average for the CET. Derecho I am not sure what you mean by backloaded El Nino winters? Apart from 1982-83, I cannot think of any other backloaded winter in an El Nino year - although the second half of winter 2015-16 was nowhere near as mild as the early part of that winter but it still was not cold.

Weather-history The winter of 1976-77 in some ways followed a similar pattern to 1981-82, a cold December (though less so than in 1981), and a cold first half of January (though in 1977 it was cold up to about the 20th), then a milder rest of the winter. Though you are not quite correct about February 1977 being the mildest for the CET for ten years at the time, as it was slightly cooler than Feb 1974. You are correct in that a SSW does not guarantee cold for the UK, as our luck is then if the northern blocking sets up favourably to influence the UK with airflows from a cold source, as the dice still has to land favourably for us in the UK. In the same way that a SSW does not guarantee cold for the UK, it does not guarantee not bumping the UK out of a cold spell either, as blocking may then reassert itself in an unfavourable position for us. One recent example is that we did get a potent cold spell in early February 2021 (and it looked promising for a cold month), but it went belly up after the 14th and turned the UK very mild (February 2021 then did the same as Feb 2009, 2012, in seeing a very mild second half after a notable cold spell earlier in the month).

reef I never thought that it was clear that a cool September had any bearing on the following winter's weather. I think, and have only ever thought that the theory only worked one way, that only warm Septembers have an effect on the following winter's weather, whereas I have never thought that there was any trend with a cooler or even near average September and the following winter's weather. The records show that it is clear that whilst it is not unheard of to get a milder winter after a cooler or even average September, it is very rare if not unheard of to get a cold winter after a warm September. It is certainly true to say that if you want cold weather in the following winter, then you do not want to see anomalous warmth in September, otherwise you can almost guarantee that it is bad news for cold weather in the winter to come, but if September is cooler or even average then it does make a colder winter to follow more likely, but it does not guarantee it by any means.

Looking at bad signals for colder winter weather in the UK, most past strong ENSO anomalies either way have co-incided with milder winter weather in the UK, and no strong ENSO anomaly has ever co-incided with a UK winter as a whole being cold. The only exceptions to strong ENSO anomalies that I can think of are; one strong El Nino did co-incide with a cold winter month (February 1983), and one strong La Nina did co-incide with a very cold winter month (December 2010), but apart from that, there has been little in the way of cold weather to speak of in the UK during strong El Nino or La Nina winters. I think if anything that the warm September = mild winter theory is even stronger still. When you look at what anomalous September warmth is (the 1961-90 September average CET is 13.6, and the 1991-2020 September average CET is 14.2), you would certainly consider a September CET of 15.0 or more as warm, and a 15.5 CET or more could be regarded as a very warm September, and by 1961-90 standards or earlier than that a September CET of more than 14.5 would be considered warm. Looking at testing the warm September = mild winter theory, I cannot think of any September in the "very warm" category (CET 15.5 and above) that has led to a cold winter; most of the winters following all Septembers of 15.5 and above were mild or very mild, and very few Septembers above 15.0 CET have even led to a cold winter either (the only exceptions that I could possibly spring to mind is that September 1961 (15.2 CET), did go on to produce a winter that had a significant cold spell in December, and again from late February and through most of March (albeit not particularly cold through most of Jan and Feb), and September 1958 (15.1 CET) did go on to produce a winter that did have a cold January (albeit not particularly cold either side of this), and another could be September 1929 (15.3 CET) did go on to produce a pretty cold February (although it was generally mild before that). Apart from that there has been little in the way of cold weather to speak of in any UK winter after a very warm September. Looking at Septembers in the average or cool category, it appears that it is still possible to have a September that it just above average (1939, 1946, 1978, 2009 low 14s CET), and get a cold winter after it, and in fact among the warmest Septembers that I could think of that have gone on to produce notable cold spells in the following winter are 1981 and 1985 (14.5 - 14.6 CET).

Chris Smith I think that if you want to experience winter cold in the UK, you do not want to see anomalous warmth in September or a strong ocean anomaly any way (ENSO, IOD), as all of these are winter killer patterns for the UK.

Judging by when the most recent solar minimum occurred in 2019, and the sort of winters that the UK experienced, it makes one think that a winter like 2020-21 may be regarded as cold in the UK (and a winter like 2017-18 as well), and certainly raises fears that it is no longer realistically possible for the sort of cold spells like the UK experienced in 2009-10, December 2010 and 2012-13 to ever develop again, and it now looks very likely as though the cold spells of this time are well and truly consigned to the history books, and there is certainly fear that a winter like 2020-21 or 2017-18 may be the modern version of 2009-10, December 2010 or 2012-13.

Weather-history I thought that there was a solar minimum in early 1977, and we actually did start to get some colder winters from then on, with 1976-77 and 1977-78 having their cold moments and then the big one was in 1978-79. In many ways winters 1976-77 and 1977-78 could be seen as setting up the pattern for the big severe one to come. Judging by your point the late 1970s must have been a rapid increase from solar minimum to maximum.

I am not sure about that - the severe winter of 1978-79 occurred shortly after the solar minimum in 1977, but solar activity was on the rise. The severe winter of 1962-63 occurred close to a solar minimum. 1947 was I believe a bit like 1978-79, occurring shortly after a solar minimum when solar activity was on the rise. I am not sure about the cold winters of the early 1940s on what solar position they occurred in. That all said, solar minimums have often coincided with winters in the UK that did have notable cold spells - such as the mid 1950s, winters 1985, 1986, 1987, and winters 1995-96 and 2009-10, December 2010, and shortly after a solar minimum (but solar activity on the rise) winter 2012-13. The solar minimum of 2019 failed to produce anything cold of note close to or shortly after it - the most we got was in 2020-21 when the pattern tried to deliver the UK a cold winter with a good amount of northern blocking, but I do not know why it happens but it just did not quite come together with the low pressure not getting far enough south for northerlies and easterlies to influence the UK for significant amounts of time. I often regard winter 2020-21 as the "missed opportunity" for a cold winter in the UK close to the most recent solar minimum. More often than not the solar cycle is more favourable for cold winter patterns in the UK close to or a just after a solar minimum. That said I can think of occasional good cold spells near solar maximum; winter 1968-69 (especially February), winter 1981-82 (especially December and first half of January), but they have been few and far between.

Penrith Snow January 2024 wasn't overly mild, it had a CET of 4.7, which is actually very close to the 1991-2020 average, although it would have been relatively mild by 1961-90 standards and earlier than that (51-80, 41-70 etc). January 2024 wasn't in the 5*s club let alone the 6*s club, which would be notably mild for January, like 2020 was in recent years. January 2024 looked promising for a colder month earlier on, especially with the fairly cold HP spell earlier on being followed by the cold northerly spell in mid-month, but it then all fell apart by the 20th and the chances of a below average month were then ruined by a very mild final third to the month, and the very mild final third of January has now just remained through the first half of February. Any chances of this winter being cold were already ruined last September with how exceptionally warm it was. It is a well known fact of the British weather patterns that anomalous warmth in September does not favour a colder winter to follow. For a high September CET, it would mostly be the result of HP over Central Europe and largely stalling low pressure areas to the west of the UK. This weather pattern in September does not favour the development of northern blocking, and northerly and easterly patterns over the UK during the following winter. Another point about winter 2023-24 is that we are approaching solar maximum, so it is not a good solar match for cold. Just after the last solar minimum, I feel that the UKs best opportunity since 2012-13 for a cold winter was in 2020-21, when we actually got close with the pattern to deliver a cold winter for the UK in 2020-21, as that winter had a good amount of northern blocking but unluckily, the low pressure in the Atlantic did not get far south enough to allow northerlies and easterlies from high latitudes to influence the UK for long periods of time, although in Scotland there were good cold spells at times. At the last solar minimum, I always think of winter 2020-21 as being the year that the UK "missed the boat" for a cold winter. It appears that for British winters, a strong ENSO anomaly either way, or a strong IOD anomaly, or anomalous warmth in the previous September, is a winter killer pattern for the devlopment of cold weather patterns in the UK. Whenever any of these situations happen, I think that you can almost guarantee that colder winter weather is already "dead in the water" before the winter even starts. If I were a betting man I would put money on the UK never again seeing a cold winter after an anomalously warm September, and that anomalous warmth in September are, and always will always be a winter killer pattern for the UK.

cheese In actual fact last month, January 2024 (in the early to middle part), for a time looked promising for a colder than average month, but it all fell apart around the 20th and the rest of the month was very mild, and it has more or less been so since January 20th until now and ongoing.

@Frigid No, 2023 did not have two record breaking warm months - only one, and that was September. June 2023 was the warmest since 1846 but that month's CET was still a fair bit below the all time warmest June CET in 1846.