Driest ten months in 100 years recorded in southern England [updated]

According to the New Scientist the last 10 months were the driest July to April for southern England in records stretching back more than 100 years, or so say the Centre for Ecology and Hydrology, which I must say is the first time that I’ve ever heard of them.

Figure 1 – Courtesy of the New Scientist

Possible discrepancy in latest July to April total

When I first read this I didn’t quite believe the claim that this arbitrary 10 month period between July 2016 and April 2017 had been the driest since 1910. I could remember the dry spell of 1976, and thought that this current dry spell couldn’t match it. I’ve now added code to my Met Office 1910 climate application, which I assumed used the same Met Office 1910 gridded rainfall data, so that I could graph any user defined period that I chose, and here are the results (fig 2).

Figure 2

As you can see 1976 was the driest July to April period since 1910, as I suspected it was, and there were four other years drier than 2016-17. So I went back to the CEH site and dug out the PDF of this April’s hydrological summary. I would include the relevant table from the summary in this article but I may well end up in prison if I did so because of the copyright clauses in it, suffice it to say they get a total of 446 mm for this period which I calculate 454.7 mm. Even if you look at the rainfall data for the ‘southern’ region, 1976 is still the driest period since 1910 for July-April rainfall and the latest total, 489.4 mm still don’t tally (fig 3).

Figure 3

Likely reason for the discrepancy

From reading the Hydrological summary, I assume that the Met office use the same gridded data set to create bespoke monthly rainfall totals for most of the regional water companies around the country, and one of them is Southern Water. I guess that the ‘southern‘ in the table of the Hydrological summary doesn’t exactly equate to the Met Office’s ‘southeast and central southern England‘ (fig 5) that they produce for their 1910 monthly climate series, in fact looking at the map from the Southern Water website (fig 4) it could be a combined area that includes Southeast Water.

Figure 4 – Courtesy of Southern Water
Figure 5 – Courtesy of the Met Office

So the difference in ‘catchment areas’ so to speak undoubtedly explains the small difference in totals that I found. But creating bespoke areas is confusing, the 1910 series that you can freely download from the Met Office includes 17 regions, some of which overlap and combine sub-regions, which makes it difficult to decide which area the climate data is for.

There is one thing that I have learnt from writing this article, and that is what an interesting website the CEH have, and what an invaluable publication the Hydrological summary is. Now why can’t the Met Office publish something similar in PDF format which they could email out to subscribers that’s full of climate data, perhaps they could call it the Monthly Weather Report?

Author: xmetman

An ex-metman passionate about all things to do with weather, climate and clouds

6 thoughts on “Driest ten months in 100 years recorded in southern England [updated]”

  1. I don’t know why there rainfall year seems to start in July, I’ve read their Hydrological summary and it gives no hint as to why.
    I can’t reproduce the totals they get, either using data for southern England or for south and southeast England, but strongly suspect that the total that the Met Office provide them is for an area that’s different again. The results that I get show 1976 as the driest July-April in the record for both areas.

  2. Over the last 10 years New Scientist (& Nature) have published so much junk & badly researched papers, so If they say water is wet…. I’d want to check that out.

    Even Wikipedia is now a more reliable source….its sad to see previously good journals go down.

  3. A look back in my stats show that 1972-73 was dryer: 285.7mm compared with 314.3mm in 2016-17.
    1975-76 was also almost as dry: 325.1mm.