A yellow rain warning has been put in place in these areas and across Scotland which will last until Sunday evening.
The downpours are due to impact Dumfries and Galloway, Ayrshire and Renfrewshire on Thursday and on Saturday and Sunday, all of Strathclyde, Central, Tayside and Fife,
Highlands and Eilean Siar, South West Scotland and Lothian Borders will also be affected by the bout of extreme weather.
Experts warn the areas most affected by the upcoming spell of bad weather are already saturated which will increase the risk of flooding.
A statement on the Met Office website reads: “There is the potential for some very unsettled weather through the coming weekend, especially across southern, central and western Scotland with periods of heavy rain expected through Saturday and, after a respite overnight, Sunday."
The Met Office said the weather could cause damage to homes and businesses, travel cancellations and power cuts.
It is thought that up to 150mm of rain could fall in the mountainous regions of Wales and Cumbria within two days.
Met Office forecaster Marco Petagna told the PA news agency: “On Thursday and Friday, a band of low pressure will start to sweep in from the north-west, and will affect areas from Cornwall to Northern Ireland.
“There is likely to be incredibly heavy wind and rain in these regions, with gales of 50-60mph in exposed areas, perhaps leading to waves of around 10-11m.
“Around 40mm of rain could fall each day in some parts”.
On Wednesday, waves brought on by Hurricane Epsilon are believed to have reached near historic highs of between 10 and 15 metres in Mullaghmore, Co Sligo, Ireland.
It comes as forecasters said Londoners could experience the wettest month for more than 150 years.
October 2020 is already the ninth rainiest month in London since 1862.
Mr Petagna said: “It could be the case that the next few days of rain could make this one of the wettest October’s London has had.”
Britons have also been warned of life-threatening floods set to impact certain regions over the weekend, as more rain falls on the already saturated ground.