A daily mean temperature of 15.35C was set, but 1995 is still hottest summer here
The announcement comes as 2025 has been declared the hottest summer on record for both the UK and Ireland overall.
The warmest summer in Northern Ireland was in 1995, when a mean temperature of 15.4C was recorded.
Temperatures were 0.05C below that this year, with an average daily of 15.35C.
In July 1995, a record-high of 31.3C was set, the same temperature that was recorded in Castlederg in July 2021.
A top temperature of 30C was recorded in Magilligan, Co Londonderry, on July 12 this year.
Izzy the dog enjoys the sunny weather at Helen’s Bay on the 25th August 2025 (Luke Jervis/Belfast Telegraph)
Four heatwaves hit the UK this summer.
The Met Office defines a heatwave as temperatures of 25C or above for at least three consecutive days.
Northern Ireland recorded its third heatwave of the summer last month, just four weeks after the previous one.
August 25 saw Northern Ireland record its warmest August Bank Holiday on record, with Magilligan weather station reaching 24.5C, surpassing the previous record of 23.8C set at Banagher, Co Londonderry, in August 1983.
In the Republic, Met Éireann said August was the fourth-warmest on record, with July ninth and June fourth, while the season’s average temperature of 16.19C set a new summer record.
The Met Office said temperatures are expected to remain in the high teens as we move into autumn, with this weekend seeing highs of around 19C across Northern Ireland alongside a mixture of sunshine and showers.
People enjoy the bank holiday weather in Newcastle, Co. Down, last month. Picture: Jonathan Porter/PressEye
Saturday will bring some warm sunshine, but it will be cloudier across parts of the west, with showers possible.
Things will become more unsettled on Sunday with stronger winds, rain and possible thunderstorms.
And as we move into the new week, expect sunshine and blustery showers, with a further risk of thunder.
The Met Office added that a summer as hot or hotter than 2025 is now 70 times more likely than it would be in a “natural” climate with no human-caused greenhouse gas emissions.
The UK’s mean temperature from June 1 to August 31 stands at 16.10C, which is 1.51C above the long-term meteorological average.
Sea Park, Holywood, last month during the warm weather
This surpasses the previous record of 15.76C set in 2018, and pushes the summer of 1976 out of the top five warmest.
Met Office scientist Dr Emily Carlisle said: “Provisional Met Office statistics show that summer 2025 is officially the warmest on record with a mean temperature of 16.10C.
People enjoy the warm weather at Sea Park, Holywood, last month
Belfast History Explained: The Story of the River Farset
“The persistent warmth this year has been driven by a combination of factors including the domination of high-pressure systems, unusually warm seas around the UK and the dry spring soils.
“These conditions have created an environment where heat builds quickly and lingers, with both maximum and minimum temperatures considerably above average.”