Last year was provisionally the second warmest on record for the UK since records began in 1884, the Met Office has said.
Only 2022, which saw temperatures exceed 40C for the first time in recorded history, was hotter.
Wales and Northern Ireland had their warmest years, with the Met Office saying climate change has made these benchmarks “significantly more likely”.
Provisional figures show 2023 had an average mean temperature of 9.97C, just behind 2022’s figure of 10.03C and ahead of 2014’s figure of 9.88C.
Last year also ranked the second warmest for the Central England Temperature, the world’s longest instrumental temperature series from 1659.
Met Office senior scientist Mike Kendon said: “The observations of the UK climate are clear. Climate change is influencing UK temperature records over the long term, with 2023 going down as another very warm year and the second warmest on record.
“Had the 2023 value occurred during the 20th century, it would have been, by far, the warmest year on record.
“While our climate will remain variable, with periods of cold and wet weather, what we have observed over recent decades is a number of high temperature records tumbling.
“We expect this pattern to continue as our climate continues to change in the coming years as a result of human-induced climate change.”
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