The Weather Warning That Still Haunts Ireland

Céad Míle Fáilte, and welcome to this week’s Letter from Ireland. I’m sitting at the kitchen table with a cup of Barry’s tea cooling down beside me. I may have to start taking it iced soon enough given that the sun has been splitting the stones over the past week across Ireland and much of Europe. How are things in your own corner of the world?

Today, I’d like to chat about a different type of weather that many of our shared ancestors would have been familiar with, as there is a far bigger story sitting behind it than you might imagine.

A Blight warning on my weather app.

Over a number of days earlier this June, a little alert kept appearing whenever I checked the weather forecast: something called a “blight warning”. If you’ve never lived in Ireland, that phrase might sound strange, even a touch alarming. But around here it is simply part of the rhythm of the summer, and most of us barely glance at it before swiping it away. And yet, when I stopped and really looked at it, I realised that there is hardly another word in our whole vocabulary of weather that carries such a weight of memory behind it.

A blight warning is now a small, modern convenience, just one notification among the football scores and the shopping reminders. But if you cast your mind back, this type of blight-friendly weather is attached to the single most devastating event in our modern Irish history.

Blight is a disease of the potato, caused by a fungus-like organism, or water mould, and it loves nothing better than the mild, damp, humid air that frequently occurs this time of year in Ireland. When the temperature stays above ten degrees, the humidity climbs close to saturation, and the dampness lingers long enough on the leaves without a breeze, then you have the perfect conditions for the spores to take hold and spread.

In weather like that, a green and healthy field of potatoes can be reduced to a blackened, rotting ruin in a matter of days. So when that combination of mild, muggy, windless weather comes over the country, out goes the warning to gardeners and farmers alike: check your crop, protect it if you can, and act before the disease takes hold.

The disease that changed Ireland.

In the mid 1840s, the blight reached Europe, probably carried across Atlantic trade routes from the Americas. It swept through the continent, ruining potato crops in Belgium, the Netherlands, France and beyond, and bringing hunger and hardship to many countries. But nowhere on earth suffered as much as Ireland.

The reason was painfully simple. So many of the poorest people in Ireland depended on the potato for almost everything they ate, often a single variety known as the Lumper, grown on tiny rented patches of ground. When that one crop failed, and then failed again the following year, there was no safety net to catch the fall of millions.

The Great Famine, An Gorta Mór, is usually dated from 1845 into the early 1850s. In that period, roughly a million people died from hunger and famine-related disease, while at least a million more left Ireland. A population of more than eight million was broken apart, and the wound of it still runs through almost every diaspora family reading this letter today.

Many of us are scattered across the world, because of those still, humid, blighted summers. So you will understand why a blight warning is never quite an ordinary thing to the Irish eye.

My grandfather and a ruined year.

This is not a long forgotten history story for my own family either. I grew up hearing how the blight struck my grandfather’s potatoes back in the 1940s, long after the Famine years, and ruined the whole crop for the season. The way it was told to me, he was absolutely distraught over it, and I don’t think that was only about the food or the money.

I do not know whether the story grew in the telling, as family stories sometimes do, but I remember the feeling of it: the sense that a failed potato crop was not just a failed crop. It was a very deep wound on top of old scars.

My grandfather’s generation could not see the blight coming. But in the 1950s, a Met Éireann meteorologist named Austin Bourke worked out a set of rules linking those exact weather conditions, the temperature, the humidity, the still air, to the likelihood of a blight outbreak. They became known as the Bourke Rules, and they turned blight from something that fell on you into something that could be forecast and prepared for in advance.

Those rules, refined and updated over the years, sit behind the modern blight-warning system that pinged on my phone throughout June. A line drawn from the hungry 1840s, through my grandfather’s ruined drills in the 1940s, all the way to a notification swiped away on a summer morning in 2026.

Even now, for all the spraying, science and warning systems, there is still nothing quite so reassuring as a stiff Irish wind drying the leaves on the crops. The same wind our ancestors must have prayed for, in summers when prayer was all they had left.

And so today the sky is blue, the fields are safe, the potatoes are growing, and I am sitting here with my tea thinking how much history can hide inside one small alert on a phone.

So, let me leave you with one question this week: Did any of your ancestors leave Ireland as a result of the Great Famine/An Gorta Mór?

Do let me know in the comments section below.

Slán for now,

Mike.