June 2026 UK Maximum Daily Temperatures in context –

Following on from my review of examining False Comparisons between 2026 and 1976 based on siting, site degradation and relocations, I would now like to put forward details of such event causes, frequencies and how instrument changes potentially misrepresent actual temperatures. This is much more technical in nature thus I am putting forward the research work kindly supplied to me by Dr Eric Huxter. This is invaluable and detailed work in three parts which I will post in full below. Eric’s excellent blog can be viewed from here – I strongly recommend following his research. https://frayedendsblog.wordpress.com/

Over to Eric

PART 1

Now the dust is settling after the ‘record’ breaking weather events towards the end of June it is time to attempt to put these into context.

There is no doubt that this has been a record breaking year, with provisionally 12 new daily records, an impressive occurrence by any standards.

However, as always we need to have a way of assessing these events and must place them, as HH Lamb insisted, with his reversal of Hutton and Lyell’s arrow of time that in weather the ‘past is the key to the present’, into historical context. Looking at the record setting events this year:

the past records have been ‘smashed’, an interesting addition to the scientific vocabulary.

However while the average change has been 2.2°C it should be noted:

1. the majority of the records were set in the LIGT era and are records that were low in the record hulls;
2. the majority of stations that set the records no longer exist;
3. apart from Mona (which had Fohn assistance), the new records have been have been set by stations CIMO3/4/5 . Kew is currently likely to be CIMO 3, as it no longer appears on the FOI list of CIMO 1/2 stations, I am still waiting for a response from the Meteorological Office about its rating.
4. The current CIMO classes of old record stations apply to the PRT era , for earlier records the CIMO class is likely to have been lower (1/2) apart from the urban stations.

The pattern of new record setting confirms that these numbers are event driven and each event is different in:

1. Meteorology;
2. antecedent conditions;
3. timing;
4. geographical location.

Hence the new records represent the maximum temperatures possible at that time of year from that particular meteorology’s temporal and spatial characteristics, based on previous weather and under current land use arrangements, measured by current metrology.

The key to understanding the records is the nature of the meteorological events and AI provides a useful summary:

Clearly plumes (Iberian or Gallic) are very much to the fore and much has been made of these increasing in frequency during the 21^st century. The term ‘Spanish plume’ was coined in 1968 and has evolved into Iberian as the events have become more common with the half wavelength shift in the jet stream bringing the Azores high over mainland Europe, leading to the Gallic plume emerging as a concept over the past 15 years. With prompting AI produced the following list of significant warming events affecting the UK, with the earliest (1788) deduced from hailstones reportedly “as large as pigeon’s eggs” as in 1808 “hailstones that killed sheep”.

It is important to distinguish between pure anticyclonic events, when the high pressure is centred over the UK and plume events, where the high pressure centre is set relative to the UK to allow hot air from continental interiors to move across the UK, just as the ‘beast from the east’ brings frigid continental air in winter. The ‘beast from the south’ does not have quite the same ring. The two source areas are over Spain and Portugal (the Iberian plume) and over France (the Gallic plume). The Iberian plume travels across the Bay of Biscay and while initially warmer, cools as it travels, while picking up moisture while the Gallic plume does not cool as much passing over the Channel but still picks up moisture. This moisture is important in plume events as the higher humidity creates warmer nights, as the dominant GHG (water vapour) is more significant, hence the next day’s warming starts from a higher temperature than would be the case in a pure anticyclonic event where lower humidity allows maximum night time radiant cooling.

AI produces a useful summary of the mechanisms and their differences.

Plotting the maximum temperatures demonstrates the increase in frequency of plume events, but interestingly the plume events show a far faster rate of increase in maximum temperatures than pure anticyclonic events. Neither trends are significant at the 1% level.

Let us focus on plumes. In a GHG warming world one would expect to find a similar increase in the maxima of these events.

What else has changed, apart from the meteorologically driven shift in the summer high pressure centre?

The most important factor is the structural changes in land use in the plume source areas and in the southern UK where the effects of the plume are amplified. AI summarises these changes for the source regions and for the UK, giving values for their impact on temperature.

This suggests that much of the observed increase in temperature is due to anthropogenic land use changes rather than anything else as the graph shows the adjusted values within a much narrower band and increasing much more slowly (again neither is significant at 1%) and brings the current records more into line with those they replaced, although July 2022 is definitely an outlier.

However there is one further adjustment to the data, which is controlled by the timing of the event relative to the summer solstice, with more insolation for longer at the solstice. With this adjustment the more recent record setting plume events of 2003 and 2026 no longer set records and 2022 falls more within meteorological reality.

While the Meteorological Office is happy to trumpet records, with flashing gifs and deeper red colours, and will explain the meteorology applying at the time, with the sub-text of ‘Climate Change’, they singularly fail to put events into the context that HH Lamb so valued.

Yes the UK climate is changing, with higher temperatures driven by well documented and explained changing weather patterns (as AI needs constantly reminding, Climate is the dependent variable) but this change is demonstrably explained by the anthropogenic land use changes and meteorological context of the events that set records, changing the upper hull of the record series event by event assisted by the failings of PRT technology, without needing to invoke GHGs.

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Part 2

The next area to look at is how the plume event developed in terms of the metrology ie the use of PRTS with their propensity to spike, especially when subject to the Aitken effect at low levels of screen ventilation (%Minimum Assumed Ventilation (%MAV)).

Using hourly data collected from weatherobs.com the graph shows the temperatures from the top performing stations and their neighbours. The graph also shows the daily records, the June record, daily maxima and the  significant undershoot for the Meteorological Office’s Red Heat Warning.

The evolution of the event follows well understood Meteorological principles and the diurnal curves are clear, although at higher values there is a tendency for the curve to be constricted, an indication of measurement issues. The event clearly follows the expected path, indicating that this was a period of uniform conditions across the southern part of the UK, and the measurements should reflect this.

Even from a distance it is clear that the maxima reported by the Meteorological Office lie well above the well defined diurnal curves shown by the hourly 1 minute reports (some stations, largely airports, at 10 minute intervals).

To appreciate the scale of the divergence from the expected diurnal curves we can zoom in on the maxima:

It is now very clear the impact that spiking of PRTs has on the daily record. The daily maxima are tabulated below:

It is important to note that the spikes are not always extreme and on occasions the temperature rise is well behaved, a small increase to peak from the previous hour, but the fact that so many of the records are set with temperature rises in the upper tail of the probability distribution is concerning as this dynamic biasing of the maximum temperature is not susceptible to geostatistical control and it will bias the national record as well as providing a biased view of UK maximum temperatures to the public as widely, and rapidly, disseminated by the Meteorological Office through social media and its pipeline to the legacy media, especially those who push the AGW agenda.

There are two other important observations from the data. The first is that on the 25^th June Merryfield was credited with the national maximum despite Yeovilton recording higher hourly temperatures. This raises questions as to Quality Control and whether the earlier record at Yeovilton would be validated. Secondly the Lingwood maximum. This is from a sheltered back garden site and is a co-operating station in the Synoptic and Climate Network, which mean the PRT sourced data (maximum and minimum) are manually recorded and the raw data are not archived. Given the clear spike at Santon Downham it definitely needs careful scrutiny. The lack of transparency in the system and the loss of raw data for a National Record is distinctly unscientific.

Data collected from stations setting Regional maxima and their near neighbours shows the scale of this issue.

There are some quite impressive spikes in these data not only from the previous hour but also from the average per minute (at short enough time intervals) where the probability is based on minute to minute changes rather than the mean per minute and therefore overestimate the true probability. Given that these temperatures were being recorded under a week of uniform meteorological conditions without the short term variations that might be used to explain away such spikes, the observed data are very telling indeed.

If we look at the theoretical diurnal curves, based on the hourly maximum at the Daily Record setting stations (Santon Downham for th 27^th June as Lingwood only reports the maximum) it can be seen that the spikes lie well above the expected convex diurnal outcome.

The expected rises to peak are tabulated, with their associated probabilities. In this case the majority of the days lie well towards the centre of the probability distribution for rising temperatures.

This shows how the scale of the deviation of the actual measurements, through capturing 1 minute PRT spikes, from the expected values under the given conditions, which are a function of siting described by CIMO class. The higher the class the smaller the area for which the station is representative. Synoptic and Climate studies need regional metrics, not those dictated by the micro-environment (often extremely influenced by anthropogenic elements) which produce micro-weather (hence micro-climate) whose dynamic impacts make its biases very difficult to eliminate from the national record.

In an age of immediate  measurement and communication it is the Metrology that conditions our world view and they who control the metrology control the message and the Meteorological Offices’s command of the message is clear, despite the flaws in the measurement system that gives rise to the records they so proudly declare.

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Part 3

Having introduced the concept of comparing events through reference to a common baseline, the ‘pre-industrial’ so beloved of Climate Scientist, who never use this fixed baseline but prefer a constantly changing 30 year horizon, which, because it changes, relieves them of any responsibility to put change into context as all difference are anomalies and there is no standardisation of deviations which would allow an understanding of events within longer term natural variability.

However let us revisit the fixed baseline concept to look at comparing two completely different events, the blocking anticyclone of 1976 and the recent Gallic plume. 1976 has always been a thorn in the side of the Climate Scientist as 1911, 1923 and 1948 as early Daily Maximum Records are difficult to argue with. At lest the recent event has got rid of 3 of the 1976 records.

To compare a blocking anticyclone to a plume we need to deconstruct the event in terms of the Meteorological variables eg antecedent conditions, current soil moisture deficit and the structural changes ie the changes in land use and atmospheric composition. Fortuitously both events started at an almost identical date, therefore summer solstice premium may be ignored. We will compare the two events based on a 1750 baseline.

Plotting the raw data, the differences are stark, a) by date:

b) by day of event (adjusted so peaks coincide):

However we do need to set the common baseline by stripping out the structural changes from 1976 to 2026 and taking into account the changes in land use and the the Soil Moisture Deficit premium and the humidity premium (negative for 1976 as nights had full cooling potential).

By date 2026 is slightly ahead:

But by day of event 1976 comes out on top:

The mean values confirm the visual assessment.  Using the raw data 2026 is +1.83°C by date and + 0.53°C by day of event (adjusted to peak) but once the variables are accounted for 1976 is ahead, even by date .

There is no need to invoke GHG changes, accounting for the Meteorological and the land use variables shows that both events are of comparable magnitude by date, with 1976 ahead by day of event, with no need to invoke anthropogenic alterations of atmospheric composition. Playing the GHG card however adds insult to injury and clearly puts 1976 even further in front. So was 1976 more significant? The data suggest it was.

Source: https://tallbloke.wordpress.com/2026/07/06/june-2026-uk-maximum-daily-temperatures-in-context/