The UK is set to see highs of up to 23C (73.4F) this weekend - well above the average maximum temperature for October, which is just 15C.
While there is some way to go to reach October's record high - 29.9C (85.8F) - set in Gravesend in 2011, the predicted highs of this weekend are still notable.
Even overnight temperatures in Plymouth on Saturday are expected to reach up to 15C (59F) - higher than Devon's October average daytime maximum of 14C (57.2F).
The warm spell is a result of a jet stream - which normally comes across the Atlantic more directly - taking a big loop down south and then coming back up and bringing all the southerly air with it, according to Met Office spokesman Grahame Madge.
The maximum average temperature in October in southern England is 14C or 15C, but places are seeing potential highs of early 20s over the next couple of days.
On Saturday, London could see highs of 21C (69.8F), 22C (71.6F) or even 23C (73.4F). Temperatures in Cardiff are expected to reach a possible 20C (68F), much warmer than the average maximum of 13.5C (56.3F).
Birmingham could hit 19C (66.2F), well above the maximum average for the West Midlands in October, which is 14C (57.2F).
Forecasters expect temperatures to come down slightly on Sunday.
Kirsty McCabe, Sky's weather producer, said while there will be further bands of wet and windy weather from the southwest this weekend, it will remain "very mild with some sunnier spells" with temperatures "well above the late October average".
She warned there would be a dip into next week with a slight change in wind direction.
Met Office meteorologist Mr Madge said of the temperatures: "It's unusual, but not exceptional. It's perhaps slightly more unusual as well in that it has been a prolonged weather pattern.
"The weather pattern that's bringing us this flow of warm air has been quite stubborn and persistent.
"And we've been in this pattern for a number of days. It's led some people to suggest that it's an Indian summer, but we're not agreeing with that.
"Traditionally an Indian summer would be where you get sunshine and still dry conditions, and obviously we've had quite a lot of wind.
"It's only the temperatures that are warmer than average."