Arthog No 3 DCNN7809 – still not good even at the third attempt. Is this the best the Met Office could manage in 2025?

52.71813 -4.00481 Met Office CIMO Assessed Class 4 Installed 14/3/2025

Arthog is a small village in mid west Wales close to the shores of Afon Mawddach at 3.6 km/2.2 miles east of Barmouth. It appears to have originally been planned as a tourist resort that was never developed. The climate at Arthog is typically wet (1,000 to 1,400mm/ 40 to 55 inches per annum) mild winters with frosts quite rare, and much lower sunshine hours than typical for south Wales. Daily temperature variation range is very modest in neither being a cold nor warm location. There have been 3 separate weather stations here since 1988 and none of them have achieved better than CIMO Class 4.

One issue that particularly surprises me regarding Met Office weather station siting is that there never seems to be any attempt to improve on past failings. It is perfectly reasonable to expect weather stations used solely for forecasting purposes to be located in sites that are not representative of the wider area’s natural climate – their function is to act as an “early warning” of ever changing conditions. However, for historic climate reporting purposes (i.e. “Climate Stations”) used in national files, it should be imperative to ensure wider area representation.

Whilst it is also perfectly reasonable (indeed often critical) to have weather stations recording micro climates for local use, such as in horticulture or transport, such sites really should not contribute to any national database. Knowledge of prevailing conditions in a Victorian walled kitchen garden such as Llysdinam is simply not relevant to national climate conditions. The suggestion that even poor sites can be indicators of the climate changing over time is even more ridiculous in that unregulated sites can experience a huge range of unnatural effects distorting readings. I often mention the example of the internal combustion engine leaf blower in use around unenclosed area screens but there are numerous other possibilities.

Since the advent of instant readout Platinum Resistance Thermometers (with all Met Office sites including manually observed ones using them since 2017 at the very latest) the likelihood of just one out of 1.440 daily readings being corrupted dramatically increases – and it only takes 1 reading to determine the day’s mean. Imagine the effect of pulling up in a car, engine running, alongside one of the Met Office’s finest to take a photograph of somewhere like this.

Returning to Arthog number 3, confirms this Met Office failure to improve siting even when relocating as recently as March last year (2025). The original Arthog site was installed in 1988 at 52.71766 -4.01504 in a small woodland clearing at Fegla Fach Farm. Simultaneous with this site’s retirement on 19/1/2023 the replacement no 2 site opened at 52.717092 -4.00829 and operated long enough to appear on my Freedom of Information requested CIMO assessment listing as below. {N.B. just look how poorly rated so many sites actually are with that entire section Classes 4 or even worse}

The No 2 site was clearly debatable that only 4 days worth of readings have actually made it into the archives. It was simultaneously closed and replaced on 14/3/2025 by the current site – all three locations shown on this map below.

I have been unable to get any ground level imagery for this current site and the aerial image from google maps is not very good. Using the transfer to “2D” tool on Google Earth Pro I was able to focus a bit more detail. Supplying ChatGPT with the Ordnance Survey sheet for topography and the headline imagery it was able to enhance details to obtain a more representative image though it does incorporate a somewhat stylised Stevenson Screen.

Whilst this is probably the best of the three locations, it will still only achieve Class 4 being so close to the significant slope, inappropriate ground cover and, from the wider viewpoint, being a very wind sheltered spot from the prevailing winds. For the purpose of supplying accurate wider area representation of the prevailing climate, this site is a dismal failure though no doubt useful for the immediate estuarine vicinity. ……a rejected site for national climate historical reconstruction.