Ashington PWS Versus Wiggonholt. A demonstration on how to do things correctly……and how definitely not to.

50.94524 -0.38524 Private Site Data records from 17/8/2020 (original installation date not yet known)

Ashington weather station (location above) is NOT an official Met Office station. It is a privately owned and operated site that lies just 7.44km/4.6 miles east northeast of Wiggonholt Met Office station. Although Ashington is just a short distance from Wiggonholt and at 18 metres higher elevation, it is an entire world apart in quality, area representation and data integrity. This post is to demonstrate how things should be done (Ashington) how they most certainly should not be done (Wiggonholt) and demonstrate the differences premium quality makes.

Firstly to confirm the locality in West Sussex.

Ashington has its own extremely detailed website displaying up to date data across a wide range of parameters and also in depth historic data freely available to view. Whilst this is a great advantage over Met office stations, it is the quality of that data that matters, so what is the site equipment actually like. From their website:

“The system consists of an anemometer and wind vane for measuring wind speed and direction, and a suite of sensors providing temperature, humidity, air pressure, rainfall, solar radiation, and ultra violet radiation measurements. The rain gauge contains a tipping spoon designed to empty each time it has collected rainfall equivalent to 0.2mm, and the number of tips is counted electronically. The temperature and humidity sensors are protected from radiation during the day by a daytime fan aspirated radiation shield to maintain accurate readings. The main sensors are mounted (along with a solar panel for power) at a height of 1.25m, except the anemometer and wind vane which are at 3.6m, and the barometer, which is indoors. Anemometer readings are corrected to the normal 10m measurement height for wind speed, as required by meteorological organisations, using a standard adjustment factor (because wind slows down near to the ground). {My bold}

The whole instrument package and mounting pole are sited away from obstructions and can be seen in this image.“

From the headline location map it is clearly shown there are no artificial heat sources within the 30 metre radius circled area and the surrounding trees are distant enough not to create shading problems – this would be rated as a CIMO Class 2 site and acceptably accurate for climate reporting purposes. The equipment, ” Davis “Vantage Pro 2 Plus” Automatic Weather Station (AWS)” is of premium quality professional standard and will cost several thousand pounds. Most importantly it has additional fan assisted ventillation to ensure adequate air velocity across the temperature sensors to avoid stagnation overheating (Aitken Effect) though in this quality of open countryside setting such problems are much less frequent than certain places that will be mentioned later.

Taken all in – very good site, very good equipment and correct World Meteorological Organisation recommended aspiration levels to the sensors – data from here will be fully reliable. A credit to the site owner whom I do not know nor have had any contact with. This is how weather stations should be operated.

I have already reviewed Wiggonholt but, just to refresh the memory, here is an image of everything wrong that possibly could be in a weather station.

The Met office has been amending many of its descriptive pages and deleting many of its former, frankly outrageous, claims of high quality. This page has removed its former detailed “bullet point” siting requirements of “desirable” and “undesirable” sites presumably as it demonstrated how so many of theirs are, in fact, highly undesirable. {My prior posts have “locked down” these details for the records}. It is even worth noting that this site even blurs out their site locations map rather than updating them. Quite pitiable really.

In the case of Wiggonholt we have unacceptable (and unnecessary) slope, absurd levels of shading, {could they have placed the screen any nearer that hedge if they had tried?} and that canopy is designed to supply shade for educational tour groups on organised field trips. The only better way to create an artificial micro climate would have been to create a walled garden around the screen, something which the Met Office has form in doing.

As for the equipment, this location is guaranteed to frequently reduce adequate wind speed for the instruments to meet performance requirements, Aitken Effect will be very regularly encountered by design. Of course, none of the Met Office antiquated Victorian designed screens have fan assisted ventilation to overcome this slack air design problem and so over record both maximum and under record minimum temperatures in such degraded sites.

Wiggonholt is officially designated CIMO Class 5 which means it meets NO STANDARDS WHATSOEVER. The only requirement to meet Class 5 is to not meet any better requirement as stated by the WMO in just one sentence.

“2.6 Class 5 (additional estimated uncertainty added by siting up to 5 °C)
Site not meeting the requirements of class 4.”

So how do observations stack up between the appallingly poor Wiggonholt and the good quality private Ashington site. Wiggonholt is a very regular star performer in both the regional and national daily extremes posting by the Met Office. Whenever I see this sort of thing I refer to Ashington as below.

Every time, Ashington {Class 2 and representing the wider surrounding area) always records cooler than Class 5 (representing an artificial micro-climate of a few square metres with no over heating protection) Wiggonholt. In this case above on the 9th May by 0.9°C. In the case below on the 5th May it was by 1.5 °C.

To add insult to all this the Met Office makes the following outrageous remarks – you almost have to admire their hubris to claim the following.

The terrible reality is that a very large proportion (over 85%) of Met Office weather stations are unfitt for purpose in climate reporting terms. Similarly many of those of amateur meteorologists are vastly superior for this purpose. I am confident that amateur sites meeting Class 1 and 2 with modern adequately ventilated instruments giving genuinely accurate readings probably outnumber those of the Met Office by a very wide margin.

Source: https://tallbloke.wordpress.com/2026/05/10/ashington-pws-versus-wiggonholt-a-demonstration-on-how-to-do-things-correctly-and-how-definitely-not-to/