Iver Water Works DCNN 4590 – An emerging pattern of selected and unsatisfactory locations.

51.51247 -0.496131 Met Office Assessed CIMO Class 4(S) & UNSATISFACTORY Installed 28/6/2016

In researching this station I discovered a seriously concerning pattern of new Met Office sites – New Site locations are NOT conforming to an even geographic spread. They are clustering in specific areas likely to misrepresent area and national climate recording.

This is a long post so firstly,

Iver Water Works weather station was installed only 8 years ago. From the start it was a poor site in the very unnatural surroundings of a water treatment works. Close to the perimeter fencing it was assessed CIMO Class 4(S) with the “S” indicating suffering from “shading” effects. This shading is almost certainly caused by the electricity pylons carrying SSE’s Iver- Longford 132kV distribution line or the separate National Grid Iver – Laleham 275kV Transmission line. Map courtesy of Open Infrastructure.

{The potential effects of such high voltage transmission lines in close proximity to modern meteorological observation technology will be the subject of a future post. Should anyone have specific information on this subject please pop details in the comments below.}

The CIMO guide specifically states “Ground covered with natural and low vegetation (

The Met Office now concede this site is officially “Unsatisfactory” for climate reporting purposes despite having only recently seen fit to install it and continuing to include its ongoing temperature readings in the historic record. From FOI request as at September 2024:-

Clearly the Iver Water Works site is below acceptable standards and its current readings should not be used for the historic temperature record.

It was seeing the above image that I suddenly realised the selective pattern of new site locations in the London area. The vehicles in the image are stored from Heathrow Airport. The Heathrow site weather station itself is very close by. Having previously considered each Met Office site in isolation and small area mapping, I opted to manually mark them on a larger area map.

The Met office states ” Stations are usually around 40 km apart, enabling us to record the weather associated with the typical low pressure and frontal systems that cross the UK.”

I took an area map of Greater London and drew a circle of 40km radius from the identified central point of the King Charles 1 statue at the top of The Mall close to Charing Cross. I then simply drew north/south, and east/west markers and went on to mark out a 12 hour clock face for reference points. Within this 40km radius are 14 currently operating Met Office weather stations supplying readings to the temperature record. Their geographic distribution is anything but even.

From midnight to 4 O’clock there is just High Beach (Class 5 and Unsatisfactory Installed 1978)

From 4 O’clock to 8 O’clock there is also just the one at Kenley Airfield (Class 4 and Satifactory installed 1988).

However, from 8 O’clock to just 10 O’clock there are……Eleven

• St James’s Park – Class 5 and Unsatisfactory installed 1903.
• Battersea Heliport – Class 5 and Unsatisfactory installed 2018
• Teddington: Bushy Park – Class 4(S) and Satisfactory installed 2017
• Wisley Class 4 and Excellent (installed 1904)
• Chertsey Abbey Meads – Class 3 and Good installed 2017 (surrounded by solar panels)
• Kew Gardens – Class 2 and Excellent installed 1910 at current site.
• Heathrow – Class 3 and Good installed 1947
• Cippenham Sewage Treatment Plant – Class 4(S) and Satisfactory installed 2017
• Iver Water Treatment Works – Class 5 and Unsatisfactory installed 2016
• RAF Northolt – Class 5 and Satisfactory installed 1947
• Amersham Field Centre – Class 4 and satisfactory installed 2015 (adjacent a National grid substation.)

From 10 O’clock to Midnight there is again just Rothamsted (Class1 and Excellent, installed 1853)

I cannot see any meteorological reasoning behind such an ongoing and increasing concentration of sites in such a small sector from west-south-west to west-north- west London whilst almost completely ignoring nearly 80% of the capital. This trend is also seen in the “Missing Met stations” with sites at Hampton Water Works (closed 2019) Northwood (closed 2015) and Hampstead (closed 2016) still reporting “climate averages” for this sector.

Even more worrying is the poor quality of the sites with 10 from 14 being in Class 4/5 and 4 from 14 considered Unsatisfactory. In fact only Rothamsted on the northern periphery near Harpenden is Class 1.

So what has happened to any north, east and south London sites? Whilst sites such as Heathrow are absurdly rated as Class 3 (subject of later analysis) and seemingly must be retained however unrepresentative their readings may be, the likes of Greenwich Observatory are immediately expunged.

It seems imperative to the Met Office that the site below at Heathrow Airport is retained and others demonstrably even more compromised are added to it…..

But simultaneously the Met Office could seemingly not find a site anywhere below (Greenwich Park Observatory) to take readings so closed down the only acceptable long term site they had for a large area around.

I am not going to conjecture why such an unrepresentative selection of weather stations has come to exist nor why it is now becoming a worsening situation just yet, though I do have my own views. I would rather ask any readers to offer their views please.

Source: https://tallbloke.wordpress.com/2024/09/26/iver-water-works-dcnn-4590-an-emerging-pattern-of-selected-and-unsatisfactory-locations/