May Day Meteorology or Mythology.

1st May 2025 the UK Meteorolgical Office invented a new Mythological Metric of Motivated Measurements. The “hottest day of the year” is now morphing down to individual days records over time. Having moved on from comparisons of the hottest day’s temperature on movable feasts like Easter and “August” bank holidays (which used to occasionally fall in September!) they have now gone full on Mayday Mayhem madness. What next, the hottest first Tuesday in June in a leap year?

This was how the UK media was instructed to portray these “amazing” records.

I found this line truly mind-boggling and frankly an insult to reader’s intelligence. “That beat the previous 1 May record of 27.4C in Lossiemouth in 1990.” Does whoever writes this stuff even know where Lossiemouth actually is? The thought process of comparing temperatures from one of the World’s largest urban heat islands with the north east coast of Scotland is frankly pathetic.

https://www.arup.com/news/londons-most-extreme-urban-heat-island-hot-spot-compared-to-five-other-global-cities-in-new-survey/

It demonstrates a tremendous amount about the intellect of the authors and those at the Met Office promoting such nonsense comparisons. However, there is much worse than this with the scientific and observational standards the Met Office has now stooped to .

Initially to study the likely representation accuracy of these urban sites. Below is the 2021 list of all England Met Office sites by CIMO Classification. obtained under Freedom of Information request covering Class 1 and 2 accurate sites

Cippenham Sewage Works appears as Class 1 BUT when challenged it was found to be a “default” human error (like Hastings and Edenbridge and so on) and is now rated as Class 4

Chertsey Abbey Mead appears as Class 2 but has since had solar panels built all around it and downgraded to Class 3 but as every impartial meteorologist would agree is really Class 5. Just to refresh the memory of how bad this site has become here is that infamous site image again.

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According to the Met Office These panels make no difference…..really?

So as it now stands the only one of those “Top Ten” that is actually considered accurate by CIMO ratings (i.e. Classes 1 or 2) is Reading University (Class 2) which I have not yet reviewed. Notably this site recorded the lowest on the list – a very scant 0.4 °C higher than recorded in North East Scotland 35 years ago and 1.6 °C lower than the April record set (two weeks earlier in the year) on the 16th April in 1949. As will be discussed later even that reading at the Reading climate science indoctrination centre is debatable.

Charlwood (Gatwick) as reviewed today is claimed to be Class 3 but is in such a site that can only really be regarded as Class 5. As demonstrated in my review it is subject to over recording in the still air conditions that prevailed yesterday by its location and enclosure. Exactly the same comments can be made about Class 3 Heathrow enclosed with its jet blast screens to the runway side and roadside metal cladding creating a wind dead spot. Again the recorded south west to south,south west air stream was exceptionally calm yesterday inevitably leading to enhanced screen readings from internal overheating in its own “walled garden” enclosure.

Perhaps most notable here is that the nearest weather station to Heathrow, Iver Water Works does NOT appear on the listing above and indeed recorded over half a degree less than Heathrow despite equivalently low wind speed. This speaks volumes for the for the poor nature of the Heathrow enclosure to read so differently. Equally odd that the Met Office overlooked the discrepancy.

RAF Northolt is almost too silly a site to take seriously at Class 5 and then subject to heavy shade. Again mast height wind speeds were negligible and like Heathrow the enclosure is metal clad. Worth noting that only Otterbourne Water Works (Class 4) sits outside the intense west London cluster of weather stations I identified in reviewing Iver. Whilst whole counties such as Derbyshire are only deemed worthy of 3 weather stations, this tiny segment of the capital warrants 11 weather stations at a ratio of one for every 14 square miles – no surprise then that a long list can be manufactured from such an unrepresentative distribution – record chasing perhaps? The Otterbourne site is effectively an industrial site and is wholly unsatisfactory.

Wisley (Class 4) is probably as unnatural as it can get in horticultural terms. It sits in a deliberately engineered environment to enhance temperatures, effectively a walled garden and is no more representative nor reliable than any other walled garden. These types of sites are meaningless in terms of the natural climate simply because they are not intended to be natural. Again any real meteorologist knows this and many amateurs must cringe when they see and hear some of the preposterous claims being made. Prior to this event there were some meteorologists on X comically running a “book” on which awful site would claim the record – Otterbourne was the favourite on the grounds it was the least publicly accessible.

Then we come to the mystery of Kew where the Met Office can’t seem to make up its mind about which CIMO category it actually is. How does this site that has not been relocated jump from an assessed Class 4 with an acknowledged “”2.5 Class 4 (additional estimated uncertainty added by siting up to 2 °C)” to a Class 2?

Has there been more motivation in “improving” the assessment procedure as there were not any reputable sites amonst the plethora of low grade West London sites? Note Kenley Airfield, also in Greater London, in the listing above – that recorded 2.5 °C lower than Kew.

So how did those other sites in the area “perform” on this mythological mayday. Well in that 40 kilometre radius from the centre of London where the St James’s Park station’s readings were being ignored courtesy of their cover being blown there is actually a Class 1 site. Rothamsted Research runs probably the UK’s best site. They are their own masters and run the site for their own scientific research – politics and ideologies are of no interest to them.

ROTHAMSTED RECORDED 26.1 °C I do not feel the need to add any more.

Source: https://tallbloke.wordpress.com/2025/05/02/may-day-meteorology-or-mythology/