It might finally be time to crack out the autumn jumpers (Picture: Getty/Metro.co.uk)

It’s been an unusually summery few days in the south of the UK – but all that might be about to come crashing to a dramatic end.

A yellow warning for heavy rain has been issued by the Met Office, coming into effect tomorrow at 9pm and lasting all the way through Friday until midnight.

It covers all of Wales, part of the West Midlands including Birmingham, and everything south of Cambridge.

The summary from the Met Office reads: ‘Occasionally heavy rain will reach southwest Britain Thursday evening, then spread across much of England and Wales on Friday.’

Those living in the areas covered by the warning are asked to watch out for spray and flooding which could increase journey times, while flooding of homes and businesses is ‘likely’.

It’s unclear whether the rain is likely to be anywhere near as severe as the weather that hit Scotland last week, turning railway lines into canals and causing travel chaos.

Yesterday, the Met Office said temperatures will drop significantly by this weekend – with parts of southern England possibly dropping by as much as 10°C from earlier this week.

The warning covers Wales and much of southern England (Picture: Metro/Met Office)

Met Office Deputy Chief Meteorologist Brent Walker said: ‘As we head through second half of this week cold air will push southwards across the country and there is a risk that showers over mountains of Scotland could turn wintry.

‘By the weekend we expect all regions of the UK to be in the cold airmass and overnight frosts are possible.

‘With high pressure continuing to dominate our weather early next week, it will start largely fine, settled, and cool by day, with cold nights and a risk of rural air frosts in places.

‘Any early morning mist or fog should clear quickly and there could be a few showers possible around some coasts at times.’

We’re about to return to a much more familiar British autumn.