The Met Office has forecast “Arctic air” will head south across the US and Canada before the jet stream moves in colder temperatures over Britain towards the end of the (October) month.
A weather chart from WXCHARTS shows a band of cold air engulf much of the country in the last few days of October.
High pressure is expected to build in the mid-Atlantic and bring “cold air” to Britain as early as next week.
Met Office forecaster Aidan McGivern said: “The air is even colder so it will be quite chilly, it looks like.
“So the features next week, a lot of dry weather in the south but it will be colder with some showers.”
BBC Weather forecasters have also warned of plunging temperatures on Wednesday night.
Forecaster Matt Taylor said: “For most of you, it is going to be quite a chilly night, with temperatures in Northern England, Scotland and Ireland very close to freezing”.
Discussing the prospect of snow in the UK this winter, the Met Office’s Aidan McGivern said: “The trend into the early part of November is actually for it to be colder than average.
“But the overall trend is for as we go into December the longer range forecast is actually for more mobility, and actually that means it will tend to be warmer than average with a bit more rain.
“So, there is still an awful lot to play for. It is way too early to say anything like that.”
But some forecasters have warned temperatures could take a nosedive towards the end of October bringing ‘substantial snowfall’ across Scotland, northern and central England.
Exacta Weather’s James Madden said November threatens a hellish cocktail of freezing temperatures, storms and howling gales.
The mercury will plunge further towards the official start of winter in December with parts of the nation even facing US-style ice storms, he added.