Rainfall variation during a year

Posted: September 17, 2015 by tchannon in Analysis, climate, weather

A post by Paul Homewood expressed surprise at comment by Philip Eden in his Sunday Telegraph newspaper column about August rainfall. Eden missed a trick, reality is more interesting. I’m responding here with a lengthy item.


How rainfall varies over the year by area for a few regional datasets. Includes data from 1770 to date. (data is provided if the details matter)

Eden is I think pushing reality in finding subset areas where August is the wettest month. Read Paul’s article here.

As I read it autumn storms originate in the tropical Atlantic bringing water which has infamy[*]. As the Atlantic cools there are fewer storms and colder air. As the year progresses into what passes as summer airflow may bring warm wet air from the south, continental Europe drying out, more infamy. We have an Indian summer lull, the Atlantic calls.


Here we can see August (8) is the most variable month.



The annual data comes from the standardisation works the author has automated. Part of this removes the annual variation, this signal being saved to disk file so producing this derivative work is a few lines of code and then process. Standardise and plot.

CSV file of the annuals and ODS spreadsheet post processing here (70kB)

The two original works are here and here as PDF

Underlying Met Office data links
Areal rainfall

Post by Tim

  1. ren says:

    Massive dangerous earthquake near Illapel (Coquimbo coast), Chile – at least 5 people killed – Pacific Ocean tsunami waves expected.


  2. ren says:

    This is the beginning of the end of the El Niño?

  3. Stephen Richards says:

    so with the NA currently cold the UK should have a drier than average winter?

  4. roger says:

    Hi ren!
    Your observations on various blogs are always interesting but their brevity makes them enigmatic, leaving laymen such as myself floundering somewhat to comprehend your intervention.
    Could you please add a sentence or two so that those of us who were streamed for Latin and arts subjects rather than sciences in the days of grammar schools can enjoy your postings to the full?

  5. tchannon says:

    Roger, Ren’s first language is Polish. Can’t speak for elsewhere, here though ask if you want clarification.
    The other Roger, Tallbloke, is happy with Ren commenting.

    Context of the Tsunami
    Last night I’d heard there was an 8.2 earthquake, local 4 metre wave warning, but no immediate major damage or wave report. The location, on the Pacific ring-of-fire is prone to huge earthquakes so I didn’t do a quick article. Similarly been recent but no high geomag at the time, this context being occasional talk about planetary alignments / solar effects.

  6. tchannon says:

    Stephen Richards, “so with the NA currently cold the UK should have a drier than average winter?”

    That looks a sensible reading but weather is very picky about pesky humans thinking they are clever. 🙂

    How about slow moving lighter rain systems? If you look at the 1766 onwards rain data in one of the PDF you will see no obvious change even though we are told humans have messed up the climate and therefore weather. Been cold before, now’t.

  7. roger says:


    I am just as happy as RogerT with ren commenting. The fault is mine not ren,s as I struggle to follow the technicalities of scientific argument.

  8. ren says:

    Roger this strong shock will cause mixing of water in the Pacific Ocean from the bottom. This may affect the Pacific Ocean temperature changes at different depths in the area of equator. See where she went the strongest wave.

  9. ren says:

    Current index El Niño.

  10. ren says:

    Here you can see how it works El Niño. You can see How does the countercurrent.

  11. oldbrew says:

    El Nino update from the Australian BOM:
    ‘A strong El Niño and record warm Indian Ocean continue’
    Issued on 15 September 2015 |

    ‘El Niño continues to strengthen. Recent oceanic and atmospheric indicators are at levels not seen since the 1997–98 El Niño. Persistently weak or reversed trade winds and a strongly negative Southern Oscillation Index (SOI), in conjunction with the ongoing warming in the tropical Pacific Ocean, indicate the El Niño is unlikely to end before early 2016.

    Climate models indicate sea surface temperatures in the central tropical Pacific are likely to rise further over the next few months, coming close to, or possibly exceeding, monthly values observed during the 1997–98 event. All models suggest the event will peak around the end of the year, followed by rapid weakening heading into autumn 2016. It is too early to accurately determine the likely pattern beyond autumn, but a continued El Niño is considered the least likely outcome at this stage.’

  12. roger says:

    rent , I am much obliged by your courteous and comprehensive reply.
    As always, your comments are not to be missed!