Capel Curig WMO03305 – ” The Snowdonia Wind Tunnel”

53.09416 -3941385 Met Office CIMO Assessed Class 2 Installed 1/1/1993

Capel Curig is located in Snowdonia, an area that has recently been renamed “ERYRI “. It regularly records the UK’s highest wind speeds and is a very wet location. The reasons for both these facets are fairly obvious from the above Ordnance Survey map indicating the exceptional close contours indicating severe slopes.

From the Met Office’s own webpage describing sites for weather stations.

Surely it is self evident that there is both “steep ground nearby that might influence the measurements” rendering this not an ideal site. Similarly “Top of a hill or steep escarpment where winds will be unrepresentative of the wider area” renders this site “Undesireable”.

For a better indication of the surroundings here is a ground level image from google maps.

At the risk of overdosing on imagery here is the 30 metre circled exclusion area for CIMO Class 2 for air temperature.

Despite roadways, vehicles, machinery and general debris the Met Office has decided this is one of the best sites in the entire UK (top 12%) and is fully representative of the wider surrounding area. Conversely the same Met office inspectorate rate perfectly flat Levens Hall as Class 5.

I asked Grok AI for an opinion on the likely wind conditions prevailing at Capel Curig.

I shall leave this one out there for people to draw their own conclusions. For my part I find it inconceivable that this site can really represent the wider area for temperature readings. It is almost certainly a very useful synoptic site for weather forecasting but surely not for historic climate and temperature reporting. It will very definitely measure high winds and, of course, that is useful to know.

Needless to say the Met office sees it differently and offers as “evidence” the site’s average temperatures for the period 1961 to 1990 i.e. a period when it never existed to provide a single raw number, thus every number is artificially fabricated from unspecified locations.

Quite miraculously the 1991 to 2020 period was “compared” to this previous period’s non-existent hard data and displays increments of 0.97°C in maximum “readings” and 0.71°C in minimums. A reminder of how representative this site may or may not be.

Now what was that famous reply from CRU head Phil Jones to Douglas Keenan………..”Why should I make the data available to you, when your aim is to try and find something wrong with it?” Well it would be very difficult to find anything wrong with Capel Curig’s 1961 to 1990 real data when there wasn’t any at all.

Source: https://tallbloke.wordpress.com/2025/12/02/capel-curig-wmo03305-the-snowdonia-wind-tunnel/