Cardinham:Bodmin WMO03823 – A seriously overrated site…..Why?

52.50206 -4.6696 Met Office CIMO Assessed Class 2 Temperature records from 1/1/1991

The Cardinham weather station lies 3 miles northeast of Bodmin at the local gliding club airfield alongside the main A30. Tim Channon reviewed the site in 2012 concluding Class 4 was the appropriate rating and, from my further research, I fully agree with that assessment. This calls the Met Office rating of Class 2 into serious question and why they so often arrive at somewhat strange views.

To refresh Tim’s own previous radius diagrams, below is the 10 metre radius circle for Class 2 from an online “map development” tool. A point to note is the length of shadow cast by known fixed heights, Stevenson screens have a base height of 1.25 metres (4 feet 1 inch) and being 0.65 metres high cast shade from 1.9 metres (6 feet 3 inches) total height. The relative shade lengths from the screen (by the central dot) can readily be compared with the tree shades which are much longer.

I assess the surrounding trees to be casting shade a minimum of 3 times greater (more likely 4) than the screen indicating a conservative height estimate of 6 metres (19 feet) though probably even higher. Below are the schematic conditions for Class 2.

It is impossible to consider this site meets the requirement of “natural and low vegetation ( when up to 20% of the area is trees up to 6 metre high.

This is by no means the only problem. This is the location of Bodmin Airfield but, as a grass strip handling mainly gliders, it is certainly not an area subject to jet blast or tarmac issues. Rather the area was extensively leveled in the past and the weather station sits at the base of a shallow bank formed from excavated material. Whilst the site elevation is quoted at 200 metres, the north of the tree line is indicated at 203 metres from Elevation Finder. The enclosure is actually located at the base of a south facing 3 metre embankment.

Rather than all the above confirmation processes, I could, of course, just publish a street view image. The site is remote from the nearest roadways but is just visible from distance.

I have specifically used other investigative means first in order to demonstrate that the Surface Stations Project uses all possible angles to corroborate details. The above image now clearly verifies the tree height calculation, proximities and the embankment.

As Tim originally assessed, and I can positively confirm, Cardinham is at best Class 4 and cannot possibly be rated as Class 2. So why has the Met Office reached this clearly impossible conclusion? My own conjecture is that they consider this WMO assessment process to be an unnecessary chore. They have their own unique system which rates Cardinham as “Good” and that is really all that they are concerned with. The sole system arbiter of their ill defined system is the Met Office themselves.

In my forthcoming review of Brooms Barn weather station (in comparison with another nearby station), I shall demonstrate how the unique Met Office grading system is totally unfit for purpose and demonstrably unsuitable for assessing climate recording. That the Met Office is simultaneously not applying WMO rating standards correctly indicates it is unfit for purpose.

Source: https://tallbloke.wordpress.com/2026/01/14/cardinhambodmin-wmo03823-a-seriously-overrated-site-why/