Which Irish Day Has The Best Weather?

Which Irish Day Has The Best Weather?

A combination of factors, the ridiculous Baltic weather whistling through the streets last evening and Bock's suggestion of a new national holiday, got me wondering: which day of the year has the finest weather?

July and August in Ireland (mileage may vary)

July and August in Ireland (mileage may vary)

Admittedly, there's probably not much to choose from; our Irish weather normally stretches from mild to miserable and back again. But it seems that every year we are treated to one sweltering weekend (somewhere between March and September) where the birds fall out of the trees with the heat, and upon which everyone remarks 'Well, I guess that was our Summer.'

I set out to discover on which day this blessed event was most likely to fall — not quite as easy a task as I thought.

First of all, I'm not talking about the single day with the highest temperature. I'm already well aware of that little nugget of trivia; I recite it smugly whenever someone from Spain talks about their 45°C Summers.

The highest temperature ever recorded in Ireland was 33.3 °C (91.9 °F) at Kilkenny Castle, County Kilkenny on 26 June 1887.()

We haven't really gotten close to it since, which kind of makes me suspect the quality of the recording devices used in the 1880's. Not to mention the state of the note-taker on a Sunday morning in June after a blistering weekend in the pub. In Kilkenny.

(You may be also interested to know how we measure up with the rest of the world. A temperature recorded in Death Valley, California, back in August 1913 reached 56.7 °C, which is 134 °F.

Holy Mother of God.)

For completeness sake:

The lowest temperature ever recorded in Ireland was −19.1 °C (−2.4 °F) at Markree Castle, County Sligo on 16 January 1881.(††)

It was only -2°C last night, but somehow 'minus two' always manages to feel about ten degrees worse in Ireland than in any other country. They say it's the moisture in the air, but I blame Fianna Fáil.

Anyway, what I was interested in finding out was the day of the year that had the highest average temperature. I did a minimal amount of Googling and was unsatisfied. Then I went over to the Met Éireann site and discovered that they don't publish their information online — just a long list of charges like:

€160 + 23% VAT (€36.80) = €196.80 for a frequency table involving wind speed, wind direction and Pasquill stability indices

I had better luck with the European Climate Assessment & Dataset project, which is part of the European Climate Support Network. They allow you to perform a custom ASCII query on twenty-five billion records and download the resulting dataset.

So, I found the maximum temperatures as recorded in Birr, County Offaly (the nearest comparable location) for the last seventy years or so (but not including the last few years for some reason, perhaps because Met Éireann are selling that data?) and downloaded a text file of comma separated values.

STAID,SOUID,DATE,TX,Q_TX
449,100449,19790418,131,0

That sort of thing.

I imported it into Excel, where I'm more comfortable, and reformatted the numbers. Then stripped off the years and made a pivot table showing the average temperatures for each day of the month.

And here are the results showing the top twenty days of the year for sunshine in Ireland (well, Birr anyway) in degrees Celsius.

19/7 19.85
10/8 19.77
7/7 19.71
28/7 19.69
23/7 19.68
2/8 19.68
20/7 19.65
29/7 19.64
5/8 19.57
5/7 19.56
4/8 19.56
27/7 19.56
15/7 19.51
14/7 19.51
25/7 19.48
24/7 19.46
18/7 19.44
3/8 19.44
26/7 19.43
21/7 19.42

 

As you can see, a full three quarters of the days are in July with the remainder in August. In fact, of the first sixty-five days in the list, only four are outside July and August. But I suppose that is to be expected.

Our clear winner (by a significant margin of 0.08°C) is July the nineteenth, which — in case you're planning a wedding, or indeed a national holiday — falls on a Friday this year.

Feel free to let me know how unscientific and flawed my method was.

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Endnotes:
  1. Wikipedia [back ↩]
  2. †† ibid. [back ↩]