Inverness DCNN0588 – The subject of urban encroachment and how this affects climate data.

57.496566 -4.221870 Never CIMO Assessed Archived temperature records from 1957 to 2012 plus a few sporadic readings to 2015

The above image is of the location of Inverness weather station which archives show was originally installed in 1951 though there are no temperature readings on file until 1957. This image dates from 1945 prior to the site’s installation and indicates what appears to be an undeveloped rural area to the north of the main urban area and east of the port. It certainly does not look remotely similar these days. Now a major industrial and retail estate area, the natural climatology will have changed out of all recognition. This report is to identify the effect this has on the Met Office representation of climate. averages and produces some unexpected results.

The site in 2003:-

Variously locally surrounded by Halfords, B & Q, and City Plumbing, the entire area for many square miles around is now a tarmac and concrete jungle. The nearest significant area of greenery is a kilometre away and that is the pitch of the Caledonian Stadium home to Inverness Caledonian Thistle Football Club.

The weather station was always manually observed, never modernised to using a Platinum resistance thermometer nor relocated. Would such a site indicate the effects caused by rampant urbanisation with significant temperature uplift especially in night time minimums becoming warmer? Well actually no and this is where double checking historic provenance is critical rather than plausible assumptions.

The headline greenfield site was actually the former RAF Invernes/Longman Airfield, a grass landing field that was subsequently developed immediately after closure in 1947. The urbanisation as the Longman Industrial Estate was rapid and by the start of the temperature readings in 1957 the area was effectively a similar concrete jungle to today. This area of Scotland had been significantly under developed prior and the issue was even discussed in Parliament* in 1957, Longman Industrial Estate was the exception at the time and not the rule for the region.

“.The following day, in a leader, the same newspaper pointed out that:

“The only points within the Highlands proper at which Government money has been spent on the erection of factories to rent are the Longman industrial estate at Inverness and at Inverasdale, in Wester Ross,…….. those factories, made possible by Government money, are being run very successfully, and in paying tribute to the Council for its work we should also pay tribute to the work which has been carried out on industrial lines as a result of Government-sponsored factories“

{*Ed nore:Control F and search under “Longman“}

Quite why the Met Office opted to open a climate reporting site here seems strange though a plausible reason may have been continuation of readings from the previous non-archived aviation readings. Whatever the reasons, the historic reality is one of a weather station being installed in what was already a dense urban environment and surviving for almost 60 years.

This tiny somewhat incongruous urban green oasis becomes similar to the likes of the Camden Square station in London. In my Camden review I noted it was a pity that the site was no longer operational as it would have been very useful in monitoring climate variations. The site had been continuously subject to UHI which would not have significantly altered over the decades – it was probably as bad 150 years ago as it would be now.

This unusual urban continuity at Inverness made me examine its “Climate Averages” record. n.b. although this data will predominantly be based on Inverness it represents a homogenised combination of surrounding stations as well as any missing readings being “infilled” from other stations.

Station: Inverness

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

12.68

5.66

38.35

1249.67

755.02

147.90

–

Climate Period: 1961-1990

Annual

11.93

5.37

46.03

1198.02

642.39

130.74

–

It is well understood that the Urban Heat Island Effect is most noted by elevation of night time minimums due to daytime absorbed heat being released at night in addition to the overall wind calming of built up areas. Had this been originally a rural site transitioning to a built up area, it would be expected for there to be a large uplift in minimums. However, this is what is actually noted.

Mean Annual Maximum Increment: 0.73 °C

Mean Annual Minimum Increment: 0.29 °C

This minimum increment is remarkably modest but notably falls exactly in line with that noted at Belfast in my previous Portglenone review where I compared climate averages across Northern Ireland. In the Belfast:New Forge review I noted that all the Belfast stations likely to comprise area data were heavily urban compromised even to the absurd extent of the (now mercifully closed) Ravenhill Road site.

Another point to consider regarding the maximum temperature increase at this Inverness site is that it may also be attributed to the huge increase in motorised vehicle movements. The vast majority will be in the daytime in such locations with literally tens of thousands of cars, vans and lorries coming, going and parking throughout the day, There has been over a five-fold increase in registered road vehicles in the period since site opening.

Thus the very large 60 year increments (1.79 °C) in night time minimums demonstrated at Killowen are almost certainly the result of comparing a modern urbanised area with data attributed to a former rural one. Conversely Inverness (and Belfast) indicate the increment of urban continuity at just 0.29 °C

It simply cannot be conclusively proved that this resultant difference of 1.5 °C is solely due to urbanisation effects from these possibly extreme examples. However, it does strongly indicate one of the many and various distorting elements that are causing the appearance of a national temperature uplift where only limited natural variation really exists.

Source: https://talkshop.blog/2026/08/30/inverness-dcnn0588-the-subject-of-urban-encroachment-and-how-this-affects-climate-data/