South Uist Range WMO03023 – Another marked down good site not “playing the game” compared with those that do.

57.357583 -7.385003 Met Office CIMO Assess Class 4 Archived Temperature records from 16/7/1996

South Uist is the second largest island of the Outer Hebrides with an area of 320 square km/124 square miles. The exposed west of the island is relatively low lying “machair” running down to a continuous sandy beach which runs from the south to north of the 33 km/20 mile long island. The east of the island is a mountainous ridge reaching over 600 metres/2000 feet amsl. Such geography makes for potential Foehn Winds to easterly/south easterly wind directions, however, such conditions are rare and unlike much of western Scotland, Foehns are exceptional events on the island. This report follows on from my Tain Range review in questioning Met Office siting assessments and the noted differences that siting can produce.

South Uist Range is a military bombing range in the same style as Holbeach, Aberporth , Tain and several others.around the UK coastline usually in remote locations. It sits towards the north west coast of the island very much surrounded by the low lying machair. When Tim Channon originally reviewed this site he went to great lengths to confirm his assessment of CIMO Class 1 by measuring the area of all possible “contaminants” to readings accuracy within the delineated 100 metre radius area of the screen. I reproduce this in full below to demonstrate the diligent lengths he went to.

This current google aerial image available confirms the area has not changed and that there is still less than the regulation maximum of 10% of the area within the circle being of an artificial nature. This site meets Class 1 on these grounds.

The next issues to address are slope and ground cover. Google streetview helpfully covers this area and again confirms nothing more than a very gentle slope and typical ground cover. As is normal this imagery foreshortens distance and the buildings to the rear are almost 100 metres distant from the screen as is shown above. The only potential nit pick is the perimeter security fencing and its possible ground level wind calming. It seems unlikely that at the distances involved and generally medium to strong prevailing winds that this will make any material difference.

A final point to consider is the potential for remote shading. The CIMO regulation for Class 1 requires

“(iii) Away from all projected shade when the sun is higher than 5°.”

Rotating the above “Streetview” image through 180° reveals the distant mountainous east of the island as below. I feel it would be unreasonable (to put it mildly) to mark down this site on the grounds of possible shading.

So far I totally agree with Tim’s assessment of Class 1 and cannot see any possible reason for the Met office to mark the site down to Class 4. So what about the Met Office’s own unique site exposure assessment system. This is largely explained in their Surface Data Users Guide as follows:

1. The site should be representative of an area up to several tens of km from the station
2. The instruments should be installed on level ground
3. There should be no steeply sloping ground in the vicinity and the site should not be in a hollow
4. The site should be well away from trees or any other large obstructions. The distance of any such object should be not less than twice the height of the object, and preferably four times the height
5. The site should be adequately protected to exclude entry by unauthorised persons
6. It must be possible to meet the exposure requirements of the raingauge, sunshine recorder and anemometer. Separate sites may be chosen for these instruments.

All the points have been covered including the all important fist point. “NatureScot” handily maps areas of Machair and on South Uist which extend to an area of over 47 square km and covering distances up to 20 km from the screen.

By every yardstick available this South Uist site meets every standard required to be of the highest Class 1 and yet the Met Office marks this down as a lowly “Class 4 (additional estimated uncertainty added by siting up to 2 °C)“

By contrast this site below is rated much better at Class 3. From YouTube

For the Met office to suggest this site surrounded by solar panels is superior to South Uist is risible and the following claims are complete nonsense. Natural ground cover? Shading? Wind sheltering? Distances from artificial structures?

“OFFICIAL
Dear Mr Sanders, thank you for your email dated June 26^th 2024. 

The Met Office is aware of the solar panels near Chertsey Abbey Meade Pumping Station Automated Weather Station. The weather station was originally given a CIMO 2 rating for temperature, however, following the installation of the solar panels this rating was adjusted to CIMO 3 in line with World Meteorological Organisation guidelines for screen temperatures due to the  artificial heat sources and reflective surfaces. ” 

Clearly dual standards are in operation in exactly the same way as this site below is also considered superior at Class 3.

Urban heavily compromised sites are seemingly perfectly acceptable to accept national records from and quote regularly as indicators of their narrative whilst much better quality sites for recording the natural environment are quietly dismissed. Both Chertsey, Heathrow and so many others of their ilk are only indicative of their unrepresentative micro climates and bear no relationship whatsoever to the real world climate……..how do these site measure up to the latest Met Office statements

Returning to South Uist, how does its data display change over time? This is difficult to actually assess as the current site only has readings from 16/7/1996 so not even the full most recent period of 1990 to 2020. The only other site on the island in recent times is Lochboisdale at the other end of the island and even this site only has data from 1/11/1990 to 1/7/2003. Although the “Scottish Red Book” lists historic sites at “Ushinish Lighthouse” and “Grogany” there are no digital records and archived manual ones stop in the 19th century.. It seems likely that any data for the South Uist area prior to 1990 is derived from homogenisation with the wider area and that rather implausibly extends up to 100 km/62 miles distant as shown below.

The nearest Barra station only gives readings from 1997 to 2007 again of no use for the 1961 to 1990 period. Skye:Lusa only operated from 1997 to 2017. The Prabost site on Skye does cover the earlier climate period with data from 1959 to 1989 but the comparative figures for 1961 to 1990 to those created for South Uist bear no similarity whatsoever. Similarly it is somewhat implausible to expect significant correlation to the highly variable climate history from the Tiree sites at 62 miles distant – particularly when South Uist is NOT quoted as a comparative on Tiree’s listing despite being at the same distance.

For the record the official 60 year increments from South Uist are as follows.

Station: South Uist Range

Climate period: 1991-2020 

Month	Maximum temperature (°C)	Minimum temperature (°C)	Days of air frost (days)	Sunshine (hours)	Rainfall (mm)	Days of rainfall ≥1 mm (days)	Monthly mean wind speed at 10 m (knots)

Annual

11.74

7.04

13.49

–

1201.55

205.24

15.07

Climate Period: 1961-1990

Annual

10.91

6.29

20.40

–

1234.68

226.24

–

Claimed 60 year increments of 0.83°C in mean maximums and 0.75°C in mean minimums. Again much different to those claimed for the likes of Heathrow in my Tain Range review. Conversely though, traveling from the north west to a relatively south easterly extreme, these figures contrast with those of Lowestoft. In this case precisely NONE of these stations quoted actually exist – all of them are long closed with the “undead” Scole. site which produced its last readings over 46 years ago.

Station: Lowestoft

Climate period: 1991-2020  

Month	Maximum temperature (°C)	Minimum temperature (°C)	Days of air frost (days)	Sunshine (hours)	Rainfall (mm)	Days of rainfall ≥1 mm (days)	Monthly mean wind speed at 10 m (knots)

Annual

13.85

7.69

21.67

1618.80

639.95

116.51

–

Climate Period: 1961-1990

Annual

12.76

6.61

34.17

1526.74

583.47

115.32

–

Claimed 60 year increments of 1.09°C in mean maximums and 1.08°C in mean minimums. – and all from non-existient locations whose data is subsequently deleted from view.

The Met Office is playing games with its siting classifications, how it homogenises and adjusts data and even creates averages from site’s readings that the public is not allowed to know whether or not they even exist. This level of deception cannot continue.

Source: https://talkshop.blog/2026/08/24/south-uist-range-wmo03023-another-marked-down-good-site-not-playing-the-game-compared-with-those-that-do/