IRELAND RECORDED ITS hottest summer on record this year, but it wasn’t just daytime temperatures that contributed to this.
Many found it difficult to sleep during warm nights this summer and it’s now being warned that human-caused climate change made these relatively hot nights 40 times more likely.
It’s also being warned that these warm summer nights are set to become more regular due to climate change.
That’s according to research published today by researchers from Maynooth University and Met Éireann, which outlines the influence of climate change on record temperatures experienced in Ireland over the summer.
This summer was provisionally the warmest on record nationally, with a mean temperature of 16.19°C.
That overtakes the previous record set in 1995 with a mean temperature of 16.11°C.
Researchers found that human-caused climate change made the warm summer days nine times more likely, but caused the warm summer nights to be 40 times more likely.
While day-time temperatures were not as warm as previous record-breaking summers, high night-time temperatures pushed the temperature average up to break the warmest summer record.
The researchers said these warm nights kept overall temperatures high, while dry soils following a warm and relatively dry spring allowed heat to build.
The researchers also pointed to other factors, such as the influence of multiple European heat domes throughout the summer and continuous marine heatwaves in Irish waters.
There was a severe marine heatwave in May, which saw sea surface temperatures in Irish waters up to 2.3 degrees above average, followed by numerous more throughout the summer months.
Pre-industrial comparison
The temperatures recorded this summer have been compared to temperatures in the “pre-industrial climate”, which is defined as the period from 1850-1900.
The minimum temperatures experienced this summer are 40 times more likely than compared to a pre-industrial climate.
That means the average minimum temperatures experienced in 2025 are now a 1-in-15 year occurrence, while in the pre-industrial climate they may have been expected to occur once every 600 years.
Meanwhile, maximum temperatures experienced this summer are nine times more likely than compared to the pre-industrial climate.
The researchers also noted that both maximum and minimum average summer temperatures warmed this year by around 1°C, compared with an increase of 1.3°C globally.
Should global temperatures increase by 2°C globally, the average nighttime temperatures experienced this summer will become a 1-in-5 year occurrence, while the average daytime temperatures will become a 1-in-3 year event.
Warming climate
Dr Claire Bergin of Maynooth University said that while we have “known for years that society’s reliance on fossil fuels has been leading to a warming climate”, there is now Irish-based analysis that shows “for certain that Ireland is seeing a direct effect of global climate change”.
Bergin said the regularity of increased summer heat is only set to increase in the future with increased global warming and warned that most houses in Ireland are “not built with these rising temperatures in mind”.
She said that adapting houses now will be important, particularly for warm summer nights which are set to become more regular.
Meanwhile, Paul Moore, climatologist at Met Éireann, explained the overall meteorological setup for Ireland this summer was “fairly typical”, as opposed to the two previous warmest summers on record for Ireland, 1995 and 1976, which “were not typical at all”
“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,” said Moore.
Elsewhere, Dr. Pádraig Flattery, senior climatologist at Met Éireann, added that what would have been expected only once in 600 years in a pre-industrial climate is now on course to become “commonplace if global warming continues at current or higher rates”.
He said this is a “stark reminder of the urgent need to reduce greenhouse gas emissions to net zero in order to avoid the worst impacts of climate change”.
It was also warned by the researchers that the unusually warm waters around the Irish coast has played a “key role in keeping overall temperatures high, particularly at night”.
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