2 January – Today, the lowest temperature recorded in Ireland in the 20th century was −18.8 °C (−1.8 °F) at Lullymore, County Kildare. (The lowest on record, in 1881, was −19.1 °C.)[1]
15 April – Three teenagers were killed and others were seriously injured while orienteering in the Glen of Imaal military training area in Country Wicklow when they accidentally triggered an unexploded shell left by the military after a training exercise.[2]
May
10 May – Petrol shortages due to a crisis in the Middle East caused long delays at petrol stations in Ireland.
31 May – The Minister for Posts and Telegraphs, Pádraig Faulkner, launched a second national radio station, RTÉ Radio 2. The music station was intended to appeal to "women at home, motorists, workers of industry as well as many young people" and to broadcast for 19½hours per day. Listeners heard the voice of Brendan Balfe introducing the first programme presenter, Larry Gogan, who began by playing Like Clockwork by the Boomtown Rats. The arrival of Radio 2 caused the original RTÉ Radio station to be renamed RTÉ Radio 1. In 1988, RTÉ Radio 2 was renamed 2FM, and was renamed again in 2000 as RTÉ 2FM.[3][4]
June
2 June – Protesters opposed to the building of civic offices on the site of Viking excavations in Wood Quay, Dublin, occupied the area.
9 August – The first group of Vietnamese refugees arrived in Ireland.
27 August
British retired Admiral Lord Mountbatten (a cousin to the Queen), and two 15-year-olds, his nephew and boatboy Paul Maxwell, were killed by a bomb planted on his boat in County Sligo where he was holidaying. The Dowager Lady Brabourne died the following day of her injuries.
29 September – Pope John Paul II arrived at Dublin Airport for a three-day visit to Ireland. A quarter of the population, 1.25 million people, welcomed him at a mass in the Phoenix Park. Later, he spoke to 200,000 people at Drogheda, County Louth. He returned to Dublin in the evening where 750,000 people watched his motorcade passing through the city.
30 September – The Pope addressed 285,000 people at a youth rally in Galway before travelling to Knock where a further 300,000 people heard him speak. He also visited Clonmacnoise.
October
1 October – The Pope visited the Nunciature at Maynooth College and celebrated mass before 400,000 people in Limerick. He then left Shannon Airport for Boston in the United States.
November
23 November – In Dublin, IRA member Thomas McMahon was sentenced to life imprisonment for the murder of Lord Mountbatten.
5 December – Jack Lynch announced his resignation as Taoiseach and leader of Fianna Fáil. He had led the party for thirteen years, spending nine as Taoiseach.
7 December
Charles Haughey was elected leader of the Fianna Fáil party.
31 December – 1979 was the worst year ever for industrial disputes in Ireland, costing the economy over 1,460,000 working days.
Undated – The Central Bank of Ireland postponed the issue of a new £20 note, blue in colour, bearing an image of the poet W. B. Yeats until January 1980, due to financial problems.