The Met Office has issued a warning of "heavy and persistent rain" across many parts of the country.
The alert covers south west Scotland, Lothian, the Scottish Borders, Central, Tayside, Fife and Strathclyde "and loads of other places - you just watch."
The warning comes after some unseasonably fine and warm weather for autumn - temperatures last week were as high as midsummer in some parts of the sweltering country.
But the fine weather is on it's way out, the Met Office warns.
"Yeah, that about sums it up," said a spokesman. "The clocks go back at the end of the month - you get that extra hour in bed, but it means winter's really on its way."
And the end of British Summer Time means a change in the weather.
"That tells us that there will probably be some bad weather - we think. Well, we're pretty sure anyway. Particularly in Scotland and up north and loads of other places - you just watch. We might even get some in the south - you never know, do you?
"You know, heavy and persistent rain and all that... snow, fog. It's going to be crap really. And sometimes, cold - even very cold.
"We've studied weather from previous winters and it all looks pretty much the same every year. So, yeah - you have been warned!"