As we progress into November (from around the 3rd), high pressure will become the dominating feature, and this may allow temperatures to take a dip, with the arrival of frost, fog and generally chilly conditions thanks to a Siberian air mass fringing into the UK.
During the final week of October, a grinding, slow lift in temperatures will affect the UK. 18C, 64F, is possible across Southern Counties on Thursday, with 12-16C(up to 61F) being more typical elsewhere. However, thereafter, the area of high pressure that will give us settled conditions, is forecast to head toward Greenland.
This could realign the wind direction back to the North East, and provide the scope for much cooler conditions. Night frosts, fog and rain showers are all a theme of the early November forecast. Due to the Easterly wind, rain is more likely across Eastern areas, with sunny spells in the West, and overnight frosts.
Of course, this forecast has moderate confidence, and I'd suggest staying tuned for further updates.
Slow rise in temperatures, overnight frosts for the first half of the period in Scotland and perhaps rural Wales/ Northern Ireland dying out.
Drizzly rain in the South on Monday dying out to give very dry, frost free conditions for the first half of the week, before temperatures begin to soar mid week. 20C is possible somewhere in the South of England on Friday.
28th October, Halloween & up to the 2nd of November:
Temperatures very slowly returning to normal. Wind becoming very light, with a low frost risk.
By Tuesday 1st November, there is a good chance that temperatures will be at or below the seasonal average, with rain showers across Eastern Counties.
2nd November - 5th November:
Slow progression into cool, settled and blocked (Atlantic) conditions providing nice, crisp Autumn weather. Temperatures around or slightly below the seasonal average. With a risk of frost, in the Countryside. This risk growing daily.