According to provisional figures every month was hotter than average except December, when there was cold snap.
The year’s average temperature is likely beat the previous all-time high of 9.88C, set in 2014, the Met Office predicted.
The exact temperature registered over the year is set to be confirmed in the New Year.
Dr Mark McCarthy, a senior climate scientist at the Met Office, said the provisional figures are in line with the “genuine impacts we expect as a result of human-induced climate change”.
He added: “Although it doesn’t mean every year will be the warmest on record, climate change continues to increase the chances of increasingly warm years over the coming decades.”
The UK experienced its fourth warmest summer on record, as temperatures broke the 40C mark for the first time.
During the intense heat in July, the Met Office issued its first ever red warning for extreme heat with forest and park fires breaking out across the UK with firefighers describing conditions as ‘like a tinder box’.
The temperatures seen in mid-July would have been “extremely unlikely in the pre-industrial period - the era before humanity started emitting lots of greenhouse gases,” Dr McCarthy said.
He added: “As we have seen in the first two weeks of December, our climate is still subject to notable cold spells during the winter season, but our observational data show these have generally become less frequent and less severe as our climate warms.”
A new record UK high of 40.3C was recorded at Coningsby in Lincolnshire on July 19. An official drought was declared in large parts of England in August, with hospipe bans in some areas.
Meanwhile, autumn was one of the UK’s warmest on record with November being 1.8C above average, according to the Met Office. That made it the third warmest on record, outstripped only by 2006 and 2011.
There were also freak weather events throughout the year. In February, Storm Franklin became the third named storm to hit the UK in a week - after Dudley and Eunice.
The Met Office said last week it was expecting 2023 to be warmer than this year, and one of the hottest on record.
Predictions suggest it will be the 10th year in a row where the global temperature is at least 1C above average.
Scientific evidence shows that climate change is driving up the global temperature.
Governments around the world have promised to cut emissions to keep temperature rises below 1.5C. The figure has been
In a separate report, the National Trust warned that extreme weather seen throughout the year would be likely to become normal.
The charity said high temperatures, droughts and storms will be commonplace challenges for the future.
In its annual report is said this year was a “stark illustration” of the difficulties many UK species could face without more action to tackle climate change.
The hot summer and months of low rainfall dried up rivers, fragile chalk streams and ponds, damaged crops and natural habitats, and fuelled wildfires that destroyed landscapes, the charity said.
The National Trust’s climate change adviser, Keith Jones, said there was “no escaping” how challenging this year’s weather had been for nature.
He said: “Drought, high temperatures, back-to-back storms, unseasonal heat, the recent cold snap and floods means nature, like us, is having to cope with a new litany of weather extremes”