It will be the warmest year on record for the UK in 2022, according to the Met Office.
The UK experienced a notable cold snap in December but the figures show that the month was hotter than average.
The previous all-time high of 9.88C was set in 2014).
The exact mean temperature will be confirmed in the new year according to the head of the Met Office.
"While many will remember the summer's extreme heat, what has been noteworthy this year has been the relatively consistent heat through the year, with every month except December being warmer than average."
He said the figures are in line with what he expects from climate change.
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 had its fourth warmest summer on record in June, with temperatures reaching 40C for the first time.
The Met Office issued a red warning for extreme heat.
Extreme weather throughout the year has set a benchmark for what a typical year could be like according to a report by the National Trust.
Major challenges for nature will be created in the years to come due to high temperatures, dry conditions and storms.
This year was an illustration of the difficulties many UK species could face without more action to tackle climate change.
The charity said that the hot summer and months of low precipitation dried up rivers, fragile chalk streams and ponds, damaged crops and natural habitats, and caused fires.
The homes of rare sand lizards were destroyed by the fires on National Trust land.
According to the National Trust's climate change adviser, there was no escaping how challenging this year's weather had been.
"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 variety of weather extremes."
He said weather experts predicted the future would be very dry and hot.