LetItSnow!

CryoraptorA303 How lovely those 1960s summers must have been… Some didn’t exceeed 25C! What a different world we live in now. Makes you wonder what the theoretical lowest possible maximum could be for a summer, in keeping with the original theme of the thread. Im loving the open discussion here though.

Summer8906 August 2023 really was so non-descript honestly. The month didn't reach 30C locally (neither did July!). It began cold and wet and ended cool, but the middle section had a lot of vaguely warm but unsettled patterns that meant a lot of days in the low to mid-20s. It honestly did feel a bit retro, like how in the old days you've have south-easterly but only get the temperature in the mid/upper 20s. We very much escaped the hot weather that month. Sort of was a very typical 21st century changeable August.

CryoraptorA303 I sort of feel like 1990 was the first version of our sort of typical late 2010s/2020s summer in a way; one poor month, one mixed month that ends up with a very hot spell and then one month with a serious heatwave. Indeed, I've seen people discuss summer 1990 very similarly to summer 2019; no one can seem to make up their mind if it was good or mixed!

Derecho All conjecture from me at this point but I wouldn't be surprised to see high pressure nose in from the south (See my latest Model Output blabber if interested). I wonder if this April may pan out like a warmer version of April 1987; very warm but not overly dry due to an unsettled start. I honestly would not be ruling out a 11+C CET this April already, though a northerly dominated second half could put a quick death to this idea. April 1995 is a good example of a very warm April turning into a mild April due to a cold second-half. Wouldn't want to bet on that at this time though.

The GFS 12z sees a different, though not inconceivable route to high pressure. With such a wad of unusually warm air over Europe for April and a return of the warm SST anomalies around the Azores, it's entirely possible this could promote a ridge of high pressure to develop into a more substatial feature. Day 10 shows the first 20C appearing on the temperature projection map in the London area. I think if we do see high pressure develop from our south it would easily get us into the range of 19-23C providing there is ample clear sky. The sun is getting stronger very quickly and the continent is warm. All very un-April like patterns though, it has to be said. Indeed, the charts look very similar to late January and much of February when persistent high pressure to our south kept us bathed in south-westerly winds. At times (late January) it ridged high enough to bring in inversion cold in the extreme south-east; this time though it's April and that increase in pressure would bring our first proper warm spell of the year. Not from a Scandinavian high like usual though. Indeed, without steering the conversation elsewhere it's got a very "new normal" look to it, though for now it would probably be very welcomed by almost the entire UK... you might even convince me into it! The devil is in the detail though and the previous run had cool N/NW winds for the same date so it is not a guarantee at this time, but a possibility, and as explained, probably not an unlikely possibility with such a loaded atmosphere. Don't send me hateful messages if low pressure is still dominating on the 12th!

Summer8906 I perhaps wonder if this is a symptom of the rising Hadley Cell. Poor summer months in times gone by were usually very cool but weren't always remarked as extremely dull. Due to weaker heights to our south, low pressure often had an easier time pushing straight through or even becoming a cut off low (July 1987) that wandered around for days. That happened a lot, yes, but I suppose it did allow for more PM air which at times was more showery. It could also explain somewhat our less thundery summers as if you look at the reports from the very poorest summers, they often had very severe thunderstorms which made them very interesting. Summers like 1980, 1985, 1987 etc all had severe thundery spells and not always from plumes. I think the more southerly track lead to "different" types of unsettled conditions and also N Atlantic ridges which brought cool but dry spells of weather which are almost non-existent now. Instead nowadays, with high pressure becoming semi-permanently fixed over Iberia, the areas of low pressure become stuck and often have a TM airmass associated with them, which brings unexceptional days but very mild nights and a whole lot of cloud and oddly, perhaps less thunder. It also means those cool ridges become harder to maintain because the forcing is coming from the south with these heat pulses wafting up. Short version: Pre-1990s could often be cool, dull and wet, but could have different types of "poor" conditions which were usually brighter and also more convective, but now we have more humid, boring south-westerly conditions due to a semi-permanent southerly quadrant to our summer winds. Just a thought. It's basically what's happeend to our winters so why not our summers too. If this needs to be moved elsewhere, .

My memories of each August and then my ranking of them... August 2010 I remember very little of except vividly the 3rd and the 4th. The 3rd I had a day out and took the Woolwich Ferry. The weather was mostly cloudy and I remember the skyline to the north-west being very black. The 4th actually brought a thunderstorm back home and interestingly it came from a weather front pulling down cool, northwesterly winds. Proof you don't need hot weather for thunderstorms. August 2011 I literally remember nothing about, but considering my aversion to hot and humid weather, it sounds like a month I'd appreciate. August 2012 I remember much better! I remember some severe storms early in the month, one that my dad took a video of on a cr** Blackberry; I think that was the 5th. I remember a fine and very warm spell from the 8th to the 11th with crystal blue skies. The 11th we took a day out to the Kent coast and the weather was optimum. There was a severe thunderstorm back home on the 13th which must have been the breakdown of it and the charts show this to be true with a trough pulled out west and slack S/SW winds. The rest of the month is a blur but I remember some bright but cool weather at the end of the month. August 2013 I remember a similar amount. I do vaguely remember the 1st being very hot but I much better remember the 2nd and 5th having severe thunderstorms. The rest of the month is patchy but I went on a trip to the Kent coast again around some point mid-month and it was similar weather to a year earlier. I have pictures of this day and despite the extended summer the grass was green, no heat stress. Must have been very thundery in the Folkestone area to replenish ground water levels. August 2014 I distinctly remember just feeling very autumnal with a total lack of summery conditions. I don't remember any standout conditions but rather just constantly a very October-y feel. August 2015 was variable but from memory, cool and wet overall. We had a very wet day with torrential thundery rain over Kent on the 13th. The 22nd was the only summery day of the month from memory. The end of the month was exceptionally cool with heavy rain and NE winds locally that brought in a very autumnal feel and ushered in that chilly September. August 2016 was mostly non-descript apart from being very dry. After some weak showers on the 4th I'm pretty sure it never rained again that month. I do remember the final ten days being very warm/hot. August 2017 may take the cake as the "poorest" though that may be my memory of it being stronger because I was 16 by this point. The month rained constantly and, as I've spoken about many times, was unusually thundery at times. There was very little sunshine from memory, just lots of very cool, Atlantic dominated weather. The hottest temperature all month was only about 29C for a couple days and then it turned very cool again. Very, very autumnal. August 2018 was a month of two-halves; it was very hot for about the first week, then it ushered in my most thundery period I can ever recall with heavy showers and severe thunderstorms every day from the 7th to the 12th (and almost the 13th too). The summer gave up after that and the second-half was quite non-descript and actually ended up very cool at month's end IIRC. August 2019 I spent in Kent until the 12th, then Cumbria for the rest of the month. In Kent it was unusual because those first 12 days were mostly very unsettled, Atlantic dominated and unsettled but with a south-westerly element so it was unsettled but warm. I remember the 2nd was bizarre as it was very windy but warm. The temperature cooled off a bit after that. In Cumbria the rest of the month was totally unsettled bar a short lived warm and sunny spell for a couple days which oddly I forget when was, but may have been around the 21st. It was very wet and cloudy. The 18th saw locally severe thunderstorms which caused flash flooding. To rank them is a bit hard because, as someone who hates hot weather and likes cool summer months, my ranking will be a LOT different to many. But many of these Augusts were all unsettled and even the warmer ones were never really ones to write home about like August 2020 or August 2022. 1. August 2018 2. August 2017 3. August 2015 4. August 2014 5. August 2010 6. August 2011 7. August 2016 8. August 2012 9. August 2013 10. August 2019 August 2018 being #1 may surprise you but it takes the cake for the sheer off the scale convective activity in NW Kent at the time, plus the variability made it interesting to me. August 2011 is ranked there because I just remember nothing about the month at all. August 2019 was far too humid and also personally my life wasn't going great at the time so it also gets that taken off of it I suppose.

danm 10th warmest March for the CET after the 2nd warmest February. The blowtorch goes on. The 1991-2020 average hides how exceptionally mild it was. Probably because March is one of the earliest months to rapidly warm up in the late 1980s onward.

Considering the warmest 12 month period is 11.6 and that was set back in 2006/2007, with extra warming in the atmosphere it is no longer inconceivable that a 12C CET year is possible. For interests sake only, I averaged the record warmest CET months for each month of the year and added about about half a degree to the old records (that’s being modest perhaps) and it gave an annual CET of 13.58! It would take an absolute unprecedented extreme to see this and I don’t think we will record that any time soon, but in a high emissions scenario it may not be out of the question for that to occur in like 2100 or 2150 or something.

Chilling things down a bit, I did the inverse of my hottest ever month theory and decided to try and create the coldest possible month ever. Same logic; I took three different Januaries with extreme cold spells (1841, 1881 and 1895) and modified the numbers ever so slightly in order to make sense for the surface conditions (same as I did for residual heat in July XXXX). The result was a January with a C.E.T. of exactly -5.0!

BruenSryan I certainly remember them as wet months! If March 2018 hadn't seen two snowy episodes, it would have been excessively dull and wet. I vividly remember March 30th, 2018 being absolutely horrible; dark skies and heavy rain all day with rain covering much of the country, stuck and unable to move. Came in a spell of almost zero sunshine between about March 22nd to around April 10th-ish. People remember April 2018 for the heatwave but forget the incessant cloud and held back daytime maxima in the first half and also the exceptionally unsettled end with an area of low pressure stuck in the North Sea (IIRC) and heavy rain and strong winds battering all day on the 29th. I remember that at one point people were wondering if it was going to be cold enough for snow but it wasn't in the end.

damianslaw Would be quite unlucky to get two dud years in a row. Say what you want about the 2010s but even amongst the dross, each year seemed to provide a mixed bag and pleasant conditions that were more than a month and there was variability. Sort of makes you realise how dire things are that you are nostalgic for the 2010s climatically! I remember us thinking how **** it was...

Upon thought, perhaps I am jumping the gun a little, but still - if low pressure wasn't so strong at the moment there is the possibility we could have tapped into it further and got some very warm temperatures out of it, mid/upper 20s perhaps, but as you stated, very unexceptional temperatures at the surface and a one day wonder. Indeed I imagine a lot of daytime temperatures for the first week of April will be unexceptional, just very mild by night. I have to wonder if the rising Hadley cell is playing a part in this weather pattern at the moment. Global drivers that have been similar to 1998 may be playing out but with high pressure to our south, instead of easily barrelling southward and introducing colder northerlies, the lows are further north and basically slamming against a European high. Not to say the former pattern isn't possible (May 2023 had weak pressure to our south a lot at times), but perhaps it's an example of an old weather pattern spun with a new AGW twist. Or it could be that April 2024 would have always had this exact weather pattern but that it's amplified to be extra warm aloft and that without AGW it would be 3-10C uppers but instead its 10-18C uppers now.

In Absence of True Seasons Upper air temperatures

WYorksWeather By over the UK, I mean that I can forsee an opportunity in the coming years to get a southerly with low pressure further west and an exception surge of warmth that gets the 20C up to C England so perhaps the term "over" is quite loose. I mean I don't see a 20C line clearing Lerwick come April or even May, but in an exceptional scenario I could see it climbing to the Midlands sort of area, maybe a bit further north. If the pressure was high it could perhaps last 24 hours. I'd imagine it would occur in the second half of the month.

danm I know. I chose that on purpose as I feel it avoids masking over the elephant in the room which by using the 1991-2020 average often does. Purely personal opinion but it's no good using a 1991-2020 map to convey a cold anomaly when historically it's not a cold anomaly. The summers of 2009 and 2010 were by no means cool summers, relatively speaking to average, though an average or even slightly warmer than average summer may feel positively Artic compared to other places.

WYorksWeather In case my point may have been misunderstood, my 20C line musings are not about this upcoming spell even, just the fact that if we see that that is almost a possibility now, it seriously makes me question the state of our climate and the extremes that are possible soon. I actually find it very concerning to be honest.

damianslaw I do feel a climb down of global temperatures combined with a probable La Niña will open the possibilities of some more interesting, seasonable weather in the 2025-2027 window and dare I say something more prone to the white stuff! 2024 has got 1903, 1974, 1998, 2007, 2011 etc written all over it; freaky, unseasonable, unreliable...

@WYorksWeatherAn open place to discuss any months maximum/minimum potential if desired, going off our quick chat in the model thread. My reason for my belief is on one of the GFS runs the 19C line was getting into France not especially far away off the continent though that's been cut back on the latest run. It does make me feel it is a possibility in the future though. I mean, if we could see the 10C line bathe the entire country on February 5th, 1869, goes to show anything's possible! And just for fun, but what would it take to get the 30C line over our shores? An extremely bad scenario no doubt and one we may never see (hpefully). What would that even equate to in terms of a maximum temperature in the UK?

Lacking a true spring feel so far, despite the warmer than average temperatures. There's been so much rain and cloud, even strong winds at times, that it's just felt like autumn rather than spring. The same pattern will continue into April for the forseeable future. A nice ridge with chilly nights and pleasantly mild days. Or even just for climatic normality, a Scandi high - or a northerly wind with the final tastes of winter with a novel snow cover to contrast with the daffodils and blossom, all things once possible... but now, just a forboding gloom that feels more typical of late October. I wasn't really feeling the effects of it until something switched. There's almost the feeling that the weather is being peverse on purprose.

Summer8906 July 2010 was an odd one. At the time there was extreme heat to our east (Russia had an exceptionally hot summer IIRC) and we were on the periphery of it in July. Looking at the temperature, sunshie and rainfall maps, it was actually an exceptinally hot month in the extreme east. In Scotland the maxima were below the 1961-1990 average so it truly was a grim summer month up there. Ironically, the reverse pattern occured in August 2010 where, though not warm, the north-west was slightly sunnier and drier than average but C England/East was cool (by day) and very wet. Might as well give the anomalies for each month like I did for 2009. June 2010 July 2010 August 2010 Summer 2010 Truly a very mixed bag.

Summer8906 The maxima for large swathes of the south-west in July 2009 were below average even by 1961-1990 averages though interestingly the far north was very warm. Indeed, for the northern Scotland overall it appears July 2009 was very warm.

WYorksWeather I respect that, but in a warming world and with a somewhat plausible chart, I do actually think it is indeed possible and I'd be surprised to not see an attempt at it in the next 5-15 years. All it takes is the right set up. Think back to pre-December 2015 times and pre-February 2019 times when those records seemed unlikely. I do think we're playing with variables we've not encountered in the technological forecasting world. Anyway, back to the forecast and ironically it seems the 6z is less feverish about the scale of the warmth though still manages to get the 10C over the extreme south-east but during the nighttime hours. Despite the southerly influence, it's possible that due to all the cloud and rain associated with these moisture laden southerlies we may not see overly high temperatures. I know you can usually add on a couple degrees but unless there's any sunny spells, probably temperatures pegged into the mid-teens. The C.E.T. will be bolstered by mild, cloudy nights. Further down the line (the 9th) it shows that some really wet weather (and perhaps stormy too) could come from low pressures grinding to a halt due to high pressure to our east. Ironically though on this chart any early spring warmth gets shunted west. I wonder if this will be one of those "C.E.T. disguises the fact it felt poor" kind of months. Wouldn't rule out later cold spells though. Despite the exceptional surge of warmth I'm not sold 100% it's a nailed on super warm April yet. damianslaw @WYorksWeatherJust to add, my thoughts on 30C in April are NOT about the coming April, I meant Aprils in the next 10-20 years or so. No further addition to this in this thread though, just clarifying.

raz.org.rain Considering it was virtually unseen in the UK except on extremely rare events until 2015, absolutely! Sadly, it's become less exceptional since, but for April I dare say it's not been seen in the reliable records. I'm sure someone will post a random chart from like 1982 proving me wrong, but basically yes, the 20C being in our vicinity in April is absolutely unthinkable, remarkable and extreme. Dare I say the equivalent would be the 27-28C line wafting to our south-east in mid-summer?

WYorksWeather October 2001 was wet though, not dry. It didn't have the novelty of October 1969 or October 1995 which, IIRC, were mostly fine and dry.