Brooms Barn DCNN3115 – Comparing neighbouring sites with very strange quality assessments and markedly different readings.

52,26053 0.56563 Met Office CIMO Assessed Class 3 Installed 1/6/1964

Brooms Barn is owned and operated by Rothamsted Research who are responsible for the weather stations here, as well as at Woburn, North Wyke in Devon and Rothamsted itself. I feel it is reasonable to say that if all Met Office weather stations were as well sited and maintained as those of Rothamsted Research there would be no grounds to have any concerns regarding data accuracy. Rothamsted appears to be able to do things consistently extremely well but peculiarly the Met Office does not always see it that way.

This is a review of Brooms Barn together with a revisit of the nearby Felsham station and a comparison of recent data from the two.

Brooms Barn weather station is 6 miles west of Bury St Edmunds in Suffolk in what has been an agricultural research centre for almost 70 years. For reasons I simply do not understand, the Met Office has downgraded this site to Class 3 with a potential area representation error margin of +/- 1 °C. This ranks the site the same as Heathrow airport – does any right minded person genuinely believe Brooms Barn is no better located than that at the UK’s busiest airport in an urban jungle?

Below is the 30 metre radius circle for Class 2. The site is flat, open and there are no trees near enough to cause shading or sheltering. The access “road” is a bare earth track only. This should be a perfectly reliable Class 2 site beyond reasonable doubt.

The Street View image is not particularly good but allowing for foreshortening effects, the screen (centre image) is visibly well clear of any detrimental effects.

Luckily over on the Met Office Weather Observations webpage, the site’s staff have uploaded images. This is very definitely a good site that is being very well cared for. It is very clean (as it should be) unlike so many other Met Office sites I could mention.

So how did the Met Office rate this site by their own unique rating system of Excellent, Good, Satisfactory and Unsatisfactory when I inquired under Freedom of Information request? Well obviously …….UNSATISFACTORY ! Why….was it too clean for them, too far away from heat sources, not playing ball in providing dodgy readings? I have no idea and I doubt they will tell me. But is it really plausible that an organisation of the reputation of Rothamsted Research is getting things so seriously wrong? I do not believe that for one second. An incorrect “tick box” perhaps?

So now consider Felsham some 21km (12.8 miles) to the south east of Brooms Barn with them both being at similar elevations.

Here the screen was installed 31/3/2018 also in an agricultural setting. Just in front of the heating oil storage tank, surrounded by barns, subject to deep shade from trees due south, in no enclosure whatsoever and where tractors can be seen to regularly transit past and even park in front of!

Clearly the 30 metre radius is heavily compromised as shown below.

And then the condemning street view image – this really is the fare we are being served up by the tax payer funded meteorological agency for a site specifically intended for climate reporting and not immediate weather forecasting.

The street view image from just 3 years after installation demonstrates the tree growth is now completely obscuring the screen.

In their professional opinion the Met Office claims this site is CIMO Class 3. Well it is on a par with Heathrow in being a strong candidate for Class 5 but is not remotely as good as Brooms Barn…..or is it?

That same FOI request showed the Met Office ranking Felsham in a very tiny group of elite sites marked “Excellent”! Is this a case of yet another of those “Human Errors” the Met Office is so prone to making as their systems are automatically set to default to perfection? Or is it a case that Felsham supplies the desired end result?

Under 4 months from installation, Felsham supplied the recorded hottest ever 26th July.

The reading for Brooms Barn that same day was 33.9°C being 1.7°C lower than the 35.6°C recorded at Felsham.

Just 6.3 miles to the south west of Felsham is RAF Wattisham. There the recorded maximum temperature was 34.1°C being 1.5°C lower.

11 miles to the south west of Felsham with the absurd back garden weather station reputedly recording to the 5th decimal place of a degree at Cavendish only 34.4°C was achieved – still 1.2°C cooler.

Even more surprising was the local community weather station in Felsham itself did not go past 33.7°C on its hourly bulletins.

Indeed why did the Met Office add Felsham in 2018 in the first instance? The area was already extraordinarily well served by longer term existing automatic sites. It seems difficult to refute that this was possibly previously an amateur site known to record warm and adopted by the Met Office for record chasing/hot spots similar to the likes of Frittenden and Astwood Bank.

Thus returning to the top quality reliable site (despite what the Met Office may claim) of Brooms Barn could the readings since the opening of Felsham be compared and if so what would that show?

Talkshop analyst Dave Woolcock ran a comparison of both tMax and tMin differences of Felsham versus Brooms Barn. Two inland sites so close together, at almost the same elevation and soil type should not naturally vary by much. Indeed one would expect extremes to be very similar if siting standards were the same as the Met Office claims.

The reality, however, is of significant variation with daily maximum extremes at Felsham recording, at times, in excess of 6°C hotter and 4°C colder. It is exceedingly improbable for these two proximate sites to record such variations naturally. The differences will almost certainly be artefacts of the very poor, indeed unacceptable siting standard at Felsham. Dave has offered a moving average to try to identify any seasonal trend but none is immediately apparant.

To further illustrate these differences, Dave then went to sort them by event frequency/range. The Y axis is showing daily event frequency and the X axis the astonishing range of differences.

BUT, there was much more damning analysis to come.

The daily average minimum (tMin) would also inevitably demonstrate “Time of Observation Bias” as Felsham only reports observations on a once daily basis whilst Broom Barns has been automatically reporting since 2010. This bias is known to over record minimums on a solely weather related basis with no practically adjustable mechanism. These were the findings:

The most striking issue is the temperature range scale that Dave had to use to get all the differences to fit. The distribution of differences is even more alarming below.

It is worth pausing at this moment to consider that all the above figures are from the real world numbers that have entered the UK’s historic temperature record from two neighbouring sites. There is no data manipulation, no adjustments, no cherry picking and everything is freely available to view online from the Met Office themselves. That the Met Office can routinely record such incorrect differences over a range of almost 16°C is proof positive of their gross incompetence……….from an organisation quoting annual climate variations to the second decimal place of one degree.

To study one example from a very memorable period – the 2022 heatwave period recording the UK national highest ever temperature.

Below are the minimums recorded and archived for the 18th and 19th July 2022.

…………………………………..Brooms Barn………………..Wattisham……………………….Felsham

18/7/2022…………………..16.2…………………………….16.2………………………………….12.6

19/7/2022…………………..22.7…………………………….20.8………………………………….14.1

20/7/2022…………………..18.4……………………………18.5…………………………………..18.3

The Felsham to Brooms Barn difference in physically recorded tMin for the 19th July 2022 was 8.6°C when in reality there would have been no real difference whatsoever (confirmed by Wattisham readings) – simply the antiquated artefact of over recording the previous day’s low due to time of obs bias and crude recording protocols.

WHILST THE MET OFFICE WAS SENSATIONALLY PROCLAIMING DUBIOUS NATIONAL MAXIMUM TEMPERATURE RECORDS THEY WERE ALSO KNOWINGLY MIS-RECORDING MINIMUMS, NOT ONLY AT FELSHAM, BUT LIKELY AT MOST OF THE UK’s 160 MANUALLY REPORTING CLIMATE STATIONS.

This subject line will be ongoing throughout many future reviews as it demonstrates absurd levels of gross incompetence by the Met Office. More details will emerge as the Talkshop moves closer to its reconstruction phase of the national historic temperature records. Meanwhile a further image of the Met Office claimed “Excellent” standard rated Class 3 that should now be known as “Felsham-in-the -Shade.” – A symbol of their more recent standards.

Source: https://tallbloke.wordpress.com/2026/01/16/brooms-barn-dcnn3115-comparing-neighbouring-sites-with-very-strange-quality-assessments-and-markedly-different-readings/