New research by climate scientists at Maynooth University in conjunction with Met Éireann has found Ireland's record summer night time temperatures this year were made 40 times more likely by human-caused climate change.
The report says similar warm summers are set to become more likely as climate change continues to drive global temperatures upwards.
Summer 2025 was the warmest summer in Ireland ever.
The average combined daily day time and night time temperature was 16.19C.
That broke a 30-year-old summertime temperature record of 16.11C set all the way back in 1995.
However, there was nothing extraordinary about the day time maximum temperatures which according to the researchers were not as warm as previous record-breaking summers.
Instead, it was what happened at night time that caused Ireland’s summer temperature record to be broken.
Summer time temperatures are always at their lowest in the middle of the night. That was the case this year too. What was different this time, however, was that the nights, on average, were warmer than ever before.
That was the case at most Met Éireann weather stations which, according to today’s report, recorded their highest mean minimum temperature on record.
The report highlights three key factors, all linked to climate change, that caused this to happen.
The first was that, after the warmest spring on record with very low rainfall, the soil was exceptionally dry for Ireland.
Normally, evaporation of moisture from the soil serves to cool air temperatures, especially at night time. But this year the fact that the soil was so dry weakened that evening cooling effect.
The second factor was the impact of marine heatwaves in the waters around Ireland. A severe marine heatwave during May was followed by numerous other heatwaves throughout the summer months.
These caused more of the heat emanating from southern Europe and northern Africa to be retained and weakened the cooling effect of the seas around Ireland.
The third factor influencing night time temperatures according to the climate scientists was the impact of multiple European heat domes on the continent where temperatures were exceptional.
The effect of all these factors on night time temperatures was enough to turn what would have been an average Irish summer into a record breaker, according to today’s report.
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It says maximum and minimum average summer temperatures in Ireland have increased by 1C since pre-industrial times. It also says Ireland can expect a repeat of this year’s high nighttime temperatures about once every 15 years.
This makes them 40 times more likely to occur than during pre-industrial times, when they were expected to recur only once every 600 years. That basically means never in a lifetime.
Currently the world is on course for about 3C of warming by the end of this century. The scientists predict that Ireland will experience the warm nights like this summer every second year if that happens.
Today’s report notes that although average maximum summer temperatures during daytime this year were not as extreme, they are still nine times more likely to occur than in pre-industrial times.
This was the first high-temperature rapid seasonal climate change attribution study for Ireland. It was carried out by researchers at Maynooth University and Met Éireann, under the umbrella of the WASITUS in collaboration with the World Weather Attribution team.
High temperatures set to become 'more regular and warmer'
Dr Claire Bergin, Researcher for the WASITUS project, and Maynooth University, said: "The high temperatures experienced this summer are set to become more regular and warmer.
"Most houses in Ireland are not built with these rising temperatures in mind so preparing and adapting houses now will be important for the increasing regularity of future warm summers. In particular, for those warm summer nights which are set to become more regular."
Paul Moore, Climatologist at Met Éireann, said: "The overall meteorological setup for Ireland during summer 2025 saw high pressure to the south and low pressure to the north leading to winds mostly between southerly and westerly.
"This is a fairly typical setup for Ireland in summer and led to near average sunshine and rainfall. The two previous warmest summers on record for Ireland, 1995 and 1976, were not typical at all.
"Both those summers were dominated by high pressure and were very dry and sunny by comparison. This means we have reached a point where the background warming due to climate change can transform an otherwise average season into a record warm season."
