This autumn is likely to be the third warmest on record, the Met Office said.
Unless temperatures plummet in the final few days of November, average autumn temperatures will be 1.4C above long-term average at 10.8C.
The record was set in 2006 with 11.4C; second warmest was 11.3C three years ago.
The Government’s official weather forecasters said: “Looking at individual countries, England stands out as the warmest relative to the long-term averages, while Northern Ireland was the least mild. This autumn is the third warmest for all UK countries apart from Northern Ireland, where it is the 9th warmest.
“The mild conditions through autumn follow on from a generally warm year overall, with all months except August having seen above average temperatures. The Met Office will make an early statement on the temperature for 2014 next week.
“Rainfall has been close to average for the season, despite record-breaking dry conditions across the UK in September.
“The rainfall of October and November has almost offset the very dry September for many areas, with a few areas having ‘caught up’ to the whole-autumn long-term average.”
The Meet Office said sunshine totals for the season are also close to average.
“For November so far, to the 25th of the month, it has been the joint fourth warmest for the UK in our records back to 1910. Like most individual months this year, it has been warmer than average but not remarkably so.
“It has also been wetter than average for the UK, but not record-breakingly so.”