Top ten: wettest counties in the UK

20 11 2012

The wettest areas of the UK are in the north of the west of the country, particularly where there is high ground.

The prevailing warm moist westerly winds mean that the west of the UK is more likely to receive rainfall from Atlantic weather systems. These weather systems usually move from west to east across the UK and as they do so the amount of rainfall they deposit reduces. This is because the mountains in the north and west of the UK cause lots of the rainfall to fall in those locations as the clouds are too ‘heavy’ to move over the higher ground.

The table below shows the average annual rainfall for the top ten wettest places in the UK.

Area Average annual rainfall (mm)
1 Argyllshire 2218.7
2 Dunbartonshire 1985.9
3 Inverness 1970.2
4 Merionethshire 1883.6
5 Ross and Cromarty 1799.8
6 Carnarvonshire 1793.1
7 Buteshire 1721.3
8 Kirkcudbrightshire 1638.1
9 Brecknockshire 1608.3
10 Westmorland 1604.2

You can find out more about rainfall in the UK including how much it rains and what causes rain on our website. Or you may be interested in our video which explains how we measure rainfall.


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10 responses

20 11 2012
darrog2012

George Symons would have something to say about this I’m sure!
I’m bemused and i would have to say, sceptical of your data – Westmorland no longer exists as has not done so for 30 yrs and if we are going to use the old counties, where is Cumberland?
I’m sure that you have averaged out the readings from numerous sites within those counties, but Cumberland includes Seathwaite, The Stye (the wettest place in Gt. Britian), Blencathra, etc, etc.

20 11 2012
Dave Britton

Full details of the methods used can be found at http://www.metoffice.gov.uk/climate/uk/about/methods.html.

20 11 2012
Jeremy Lampitt

Brecknockshire…Merionethshire…Westmorland… where are you getting these from? – a county atlas from the 1950s?! Please use current county or Unitary Authority areas.

20 11 2012
Dave Britton

Historic counties are used to ensure a consistent historical record that is not subject to change due to boundary changes. This allows for comparisons to be made over the whole historical record.

21 11 2012
Paul Crabtree (@pacrabtree)

I am not an expert but have an interest in rainfall data. I dont agree with the methodology behind it. Firstly using old fashioned counties, folk today will want to relate to where they live today. We all know that Seathwaite is the wettest inhabited place in the UK, which is in Cumbria. As Darrog2012 has pointed out the fells of Cumbria ex Westmorland and Cumberland boast the wettest rainfall records in history, far outstripping the mountains of Scotland. Rainfall volumes often diminish after a certain altitude.. I am keen to read a fresh article with either modern counties or places where people actually live rather than a dozen isolated rainfall sites on the sides of Scottish Mountains, many thanks
Paul C

21 11 2012
darrog2012

I’m still not convinced.
where does Cumberland come in the table? I’d be interested to know what stations were used and those which were discounted in both N.Lancs (old county that includes quite a bit of the lake District), westmorland and Cumberland.
So you are telling me that both the wettest inhabited and uninhabited (although both within the same 5×5 km grid) locations in these isles do not fall in the top 10 wettest counties?

21 11 2012
Dave Britton

Cumberland has, on average, 1331.9 mm of rain a year. This places it just outside the top 20 wettest counties in the UK. All available and quality controlled data available to the Met Office is used in compiling the avergaes over the 5km grid for each historic county of the UK.

21 11 2012
Paul Crabtree (@pacrabtree)

I still not convinced darrog2012 either – is there a link to which rainfall stations are used and their associated averages – many thanks

22 11 2012
Dave Britton

Monthly 5 x 5 km gridded data sets covering the UK have been been produced from 1910 for air temperature and rainfall amount, from 1929 for sunshine duration, and monthly and annual gridded data sets from the 1960s for around 30 other climatic parameters. The same analysis methods are employed in the production of monthly and seasonal summaries.

Download a description of the methods used to create gridded data sets from point data. This paper was published in the International Journal of Climatology v.25 (2005), pages 1041-1054.

http://www.metoffice.gov.uk/climate/uk/about/Monthly_gridded_datasets_UK.pdf (PDF, 766 kB).

22 11 2012
darrog2012

Dave, this article as certainly caused a stir for some of us in Cumbria, the local paper is interested in running an article on it as well.

you yourself could have prevented some of this in that your article SHOULD have mentioned why the old counties were used instead of the ‘new’ and also i think a line on why the wettest known location in these isles was in a county that falls outside of the top 20 would have been appropriate to.
An interesting article but unfortunately one that caused more Q’s than it answered in the first place.

Then do you really, (I think you must) expect us to believe that Cumberland can’t even make the top 20 – now that is stretching it, next you will be telling me that Norfolk came 19th.

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