December. Oh thank goodness for December to end 2022!! Cold and icy, it offered up a truly memorable snowshoe excursion up Glen Derry and over Beinn Bhreac. -17C, alpenglow, sparkling hoar frost and not a breath of wind. Yep, December was marvellous. Okay, so the pipes in our house froze, but December’s icy breath was a welcome return to something approaching vaguely normal.
By ‘normal’ in this sense I mean the traditional weather patterns of old, where we’d get colder than average months as well as warmer than average months.
It seems incredible, even now, but if you’d told me back in the rather chilly May of 2021, that May would be the last colder than average month for a year and a half…..well, even knowing what we do about how rapid and ‘baked in’ the warming trend now is, I’d still have thought you mad.
“Yeah things are bad”, I’d have said. “But they’re not THAT bad!”
Not surprising, therefore, that I spent much of the next 18 months in a strange existential anguish.
The nerdy stuff
I’ve been collecting weather data in Fife’s Lomond Hills for almost 13 years now, and at the end of each month I love crunching the numbers, plotting graphs, seeing whether each month is warmer or colder than my long-term average, and what the overall trends over time are. (Spoiler: they all go up).
13 years of data is pretty good, but it’s still a small dataset with which to calculate long-term averages for each calendar month. The Met Office uses a 30yr average, currently 1991 to 2020, but for this article I’m using my ten year average from 2011 to 2020 because….well, it’s all I have! But while ten years obviously isn’t ideal for a long-term average, it’s still a useful yardstick.
The orange line on the following chart shows my ten-year average for each calendar month in the Lomond Hills, up to May 2021. The blue line shows the actual average temperature recorded for each individual month in each year.
You can clearly see how the orange and blue lines routinely overlap and cross over. There are times when the blue line tracks higher than the orange line (meaning the month was warmer than average), and times when the blue line tracks lower than the orange line (meaning the month was colder than average).
It’s not a clockwork or symmetrical oscillation between warm and cold by any means. It’s rarely a case of one month warm, next month cold, next month warm and so on. Instead the warm/cold anomalies tend come in clusters of different lengths.
But the point is, they change frequently enough that you rarely go more than three or four months in one state before flipping back to the other. There’s at least some semblance of balance when assessed against the long-term average.
Before 2021, my longest spell of either anomaly, of either warmer or colder than average months, was a nine month run of colder than average months between September 2012 and May 2013. That’s closely followed by an eight month run of warmer than average months between December 2013 and July 2014 .
But as you can see on the next chart below, between June 2021 and November 2022, the blue line tracks above the orange line for the whole duration. A whopping 18 months above average! Ridiculous, frankly, and very possibly unprecedented.
When will it end?!
Even before 2021 I’d long posted a monthly (and very niche) graph and summary on social media at the end of each calendar month, saying if it had been warmer or colder than average in the Lomond Hills, and how many days of snow/frost etc there had been.
After June 2021, my monthly summaries got depressingly repetitive. Month after month of saying “warmer than average”, but none of the months were exceeding my long-term average by small margins. There were no minor anomalies here. Nope, every month was significantly above average.
Even in that first month the warning signs were there. It wasn’t a hot month, far from it. But the dearth of single digit nights made it my 2nd warmest June.
July and August 2021 continued the theme. Neither was hot, but again the relentless warm nights pushed the average temperatures up. Both were the warmest of those months I’d recorded. Not that I needed graphs to show me what was wrong. Everything just FELT wrong. It just didn’t feel like upland Fife that summer. Even the rain was weird:
“Heavy rain at 900ft….but 17C. In 11 years up here in the Lomonds I’ve never had weather like this, when it’s been so warm in persistent rain. Almost feels tropical out there. Even on warm wet days like this it would normally only be 12C to 14C, tops.”
(from @CountrysideBen on Twitter)
Summer 2021 was therefore the warmest I’d recorded, its mean temperature of 14.9C surpassing 2018’s by 0.4C.
I couldn’t help notice other oddities as the strange warm months racked up. The lapse rate, the traditional reduction in temperature with altitude, seemed to take a holiday.
Typically I’d expect to find readings at my weather station, just below 900ft, to differ substantially from just a couple of kilometres away at a lower elevation. But it was uniformly warm everywhere, regardless of height.
For four months, as I drove up and down our hill, to and from work every day, it was usually the same temperature at the top of the hill as at the bottom, and as a result we recorded night-time temperatures at 900ft we’d previously been unaccustomed to.
Meteorological Autumn arrived, but summer continued:
“After 10pm at 900ft and it’s still above 20C!! I promise you, that doesn’t even happen in the hottest heatwaves in July or August up here. That’s London weather. Sea level weather. Seriously freaky for this part of #Fife in September” (Twitter)
(from @CountrysideBen on Twitter)
September was the warmest I’d recorded. Come October, the lapse rate appeared to be working again but that didn’t stop it being my warmest October by some margin. November only managed 3rd warmest, but together those three months made it my warmest autumn, and my first autumn with an average temperature above 10C.
Winter approached. Surely that would offer respite? Not really. December came closest, being only my 5th warmest December. But it was still almost a full 1C above my long-term average.
Any glimmer of optimism was quickly extinguished by my 2nd warmest January and 2nd warmest February. Winter 21/22 consequently went down as my warmest winter, which went nicely with the warmest spring, summer AND autumn. A full set in just one year!
I think up to that point I’d nurtured hope. At the end of each month, when the stats confirmed yet another warmer than average month, I’d mentally reset, risk a little optimism and reassure myself that something is bound to budge eventually, and that all will be right again.
“This is just the nature of averages”, I told myself. “Long periods of one thing, then long periods of another.”
But when March 22 became the least frosty, least snowy March I’d recorded, I was seriously wondering if we’d ever get out of this groove. It started to feel like anything approaching normal, let alone cold, just wasn’t possible.
Warmer months are normal, but the persistence of warmth couldn’t be described as such. And as time went on, a sense of futility and helplessness took hold. Any optimism for a break in the routine gradually slipped away, replaced by frustration at the tedious inevitability of it all. It seemed like the normal law of averages, the normal rocking movement between one thing and the other over the long term, was over.
For someone who obsessively observes daily weather, this was a cause for both fascination and fear. I’d say 80% of me was desperate for it to end, but a good 20% was morbidly fascinated to see if it could continue. I think part of me even wanted it to continue, because it meant I could shout and rant about how utterly ridiculous and unprecedented the whole thing was.
What if it never ended? Oh the excitement!
Spring 2022 came and went, comfortably the warmest spring (again) I’d recorded even though none of the constituent months were the warmest individually. Crazily, the average night time temperatures in the Lomond Hills that spring were higher than the overall average temperature for Spring 2012!
Summer 2022 very nearly did it again, just 0.1C behind 2021’s record breaking summer. This despite the UK squeaking its first 40C day since records began, and the Lomonds reaching 30C for the first time. The latter didn’t even happen in the peak heat of the afternoon, either. Consistent with the mayhem of these new weather norms, we reached 30C just after 11am! The previous high of 28.3C, which WAS recorded in the peak heat of the afternoon in July 2013, was left in the dust. No incremental record-breaking here.
August 2022 similarly smashed the previous August’s new record average temperature by 0.5C. September teased with some early cold but eventually came in at 3rd warmest, before October 2022 blew the previous October’s record average out of the water as well. It was the warmest yet again, with an average temperature into double digits for the first time.
November, the 18th consecutive freakishly warm month, followed the script to the letter:
“The sun has set and we’re into the cold of November night. Except we aren’t. It’s currently 14C at 900ft and it’s still warmer than any November day since I started recording in 2010”
(from @CountrysideBen on Twitter)
To rub salt into the wound, on a walk in Fife that week, I picked up a tick, which was clearly enjoying the mild frost-free nights. November 2022 ended up being only 3rd warmest, but that, together with September and October, made it my warmest autumn. Again. A 10C autumn at that. Again.
By the time we got to December 2022, the only visible mention of this insane run of warmth in the media was in the context of that calendar year. Weather presenters started remarking that there had been 11 consecutive warmer than average months in 2022. Newsworthy yep, but I couldn’t understand why the other seven months of the run weren’t being mentioned.
“Will it be 12?”, folk were pondering.
I wasn’t interested. I wanted to know whether it would be 19!
I can’t really blame people for not noticing the remarkable persistence of warmth, because for the most part it hadn’t been noticeable in an ‘in your face’ way. Yes, heatwaves into the 30s in Scotland grab our attention, as does notable absence of snow or frost. But when we’re talking just a couple of degrees warmer every day, you can be forgiven for not really feeling it.
And crucially, certainly in the Lomond Hills, the bulk of the warming trends I’ve observed have been at night rather than during the day. Higher daytime temperatures are certainly pulling the averages up from above, but night-time temperatures are pushing harder from below.
It’s ironic therefore, in my neck of the woods at least, that the more our climate changes, the more our weather seems to stay the same. In the Lomond Hills we appear to be getting a narrower temperature range from day to day. Less difference between day and night.
December 2022 was therefore a bit of a shock, as it was actually rather cold even by 20th Century standards. It was my coldest month since January 2021, cold enough to be my coldest December since 2012 and…..more importantly…..cold enough to FINALLY register a colder than average month.
That was small comfort at the end of 2022, set against the backdrop of both the UK and Scotland having their warmest year and their highest temperature on record.
2022 was the UK’s first year with a mean average temperature in double digits. Plus it was the warmest year on record for the Central England Temperature (CET), the world’s longest running monthly temperature record, stretching back 364 years.
Still, given the emotion and attention I’d invested in this, a colder than average month was well worth the stress and frustration of frozen pipes, and went some way to dissipating my frustration and resignation. I might have even risked some optimism.
But there it was nonetheless. June 2021 to November 2022 – an unbroken monolith of 18 warmer than average months.
I doubted there could be many, if any, periods when we’ve had a run like this, but the absence of chatter about it online or in the media made me doubt myself.
Perhaps it wasn’t extraordinary? My dataset was meagre, after all. Just 12 years. Perhaps I’d been getting my knickers in a twist about nothing?
Nah. I was sure that the run was extraordinary in the modern era of weather measurements, but I didn’t have any long-term data to calculate that kind of thing, nor do I having the kind of mathematical brain that could make sense of it all.
Happily, Twitter came to the rescue, first in the form of a call-for-help from a fellow weather enthusiast in Fife (@fifeweather), and then from Met Office Deputy Chief Meteorologist Dan Harris (@roostweather), who went well beyond the call of duty by first clarifying what I was looking for, and then using OpenAccess data to generate stats (in his own spare time!) across a whopping 12 tabs of a spreadsheet.
He listed all the calendar months for Scotland between 1884 and 2022, showing whether they were warmer or colder than the long-term average. There was of course the question of what long term average to use, seeing as it gets recalculated every 30 years to ensure it more accurately reflects the current climate. Which, we all know, is warming.
My 2011 to 2020 average is most comparable with the current Met Office 30yr average, 1991 to 2020. He therefore listed all the monthly national anomalies for Scotland compared against that. And to my surprise, my 10yr average actually compared favourably. Of the 120 months in my long-term average, only 10 recorded the opposite anomaly to the Met Office 30yr average, although it should be noted that my dataset is just for Fife, whereas the Met Office is for the whole of Scotland.
The verdict
When the 1991-2020 Met Office average is applied to the entire monthly dataset (1884 to 2022), nothing comes close to the 18-month run between June 2021 and November 2022. The next longest run is 11 warmer than average months between October 2006 and April 2007.
The climate now is, however, warmer than 100 years ago, so using a modern long term average is obviously problematic. Dan therefore also ran every month between 1913 and 2022 against a rolling 30yr average, where the final year of the rolling average was the year of the month in question. So 1913’s months were compared against the 1884 to 1913 average. 1914’s against the 1885 to 1914 average. And so on.
Using this rolling average, similarly protracted runs of warmer than average months do start to appear. There are 11 months between November 2002 and September 2003, 12 months between February 1959 and January 1960, and a substantial 16-month run between January 1913 and April 1914. It should however be noted that when you compare that last period against the 1991-2020 long term average, 10 of those 16 months would now be colder than the average. It should also be noted that there are many different ways of calculating and comparing mean averages, each of which would give slightly different results.
Nevertheless, the 18 months between June 2021 and November 2022 do appear to have been the warmest of any 18 months on record in Scotland.
Faced with this exceptional period, and wrestling with what it might mean for all our futures, it’s easy to feel despondent. But as 2023 gets going, it is a (small, admittedly) relief to know that a colder than average month is still possible. Erm….for now.
The question then of course becomes, can one become two? Are two colder than average months on the trot still possible?
For now, I’m afraid the answer is no, because January 2023 has already chalked itself up as my 3rd warmest. The last time I had two consecutive colder than average months was April-May 2021. And to find a stretch longer than that, you have to go back almost five years to 2017/18!
I’m not sure folk realise just how extraordinary this all is. Seems it’s hard enough to get just one colder than average month these days, let alone two, and so the wait for two consecutive colder than average months continues. And for now at least, we appear to be firmly back in a familiar groove. I just hope we don’t have to spend another 18 months before we get out of it again!
(Dec 2010 on the far left, Jan 2023 on the far right)
Blue=colder than average. Green=average. Red=warmer than average
Massive thanks to Dan Harris at www.roostweather.com for his help in researching this article!