On 27 December, 1739 temperatures across Ireland fell below freezing and a frost set in. At this time, all of the potatoes intended for consumption were either still in the ground or stored in shallow pits. On the first two nights of this cold weather the frost froze nearly all of the potatoes rendering them unfit for consumption.
The cold weather and gale force winds lasted for seven weeks. The interiors of most houses were below freezing. Seaghan Ó Connaire, the parish priest of Cloyne, County Cork, recorded the event this way (translation from the original Gaelic):
The Gaels were not all weakened in Ireland
Until from the sky came the harsh east winds which left
Us in woe, pain, in debt and hardship
The cold weather not only brought hypothermia to the people, it also resulted in the death of many horses, cattle, and sheep.
The arctic-like weather, however, simply marked the beginning of the catastrophe. The spring of 1740 was cold and rainless. This was followed by a cool dry summer and then the coldest autumn in two centuries. The following winter was snowy and the summer of 1741 was marked by a drought.
There were also political factors which increased the disastrous impact on the people: Britain and Spain went to war which curtailed overseas trade and the demand for Irish beef and butter. There was a sharp recession in the economic activity in the towns.
As if weather and war were not enough, by the end of 1740 there were a series of overlapping epidemics—typhus, relapsing fever, and dysentery (known then as the bloody flux). This peaked in 1741, a year known as bliadhain an áir (the year of the slaughter). The death rate from the epidemics appears to have been greatest in the south and the west. Children and elders were most likely to die. It is estimated that at least one-fifth of the population of Munster died and that the total death toll in Ireland was between 300,000 and 400,000.
At this time there was no national system of relief, no local structures for dealing with the crisis. Both the Church of Ireland and the Catholic Church were unable to provide any meaningful relief. Among the wealthy there was a vague awareness of a link between hunger and the collapse in public health and a fear of social disorder and food riots. Their primary concern, however, was not subsistence, but the fluctuation in grain prices.
Unlike the Great Famine of a century later, this crisis did not bring about any massive emigration to the Americas. There was only a small rise in the number of emigrants from Dublin and Cork to the American colonies as cheap transatlantic transportation was still in the future.