A yellow weather warning is in place for rain and thunderstorms for most of south west Scotland, Edinburgh and the Lothians and Strathclyde on Friday between 10am and midnight.
The torrential rain and stormy weather is also forecast to hit northern England, Ireland and parts of Wales.
According to weather experts, as much as 80mm to 100mm of rain could fall in a short space of time in some areas.
A statement from the Met Office read: “Heavy showers are expected across much of the UK on Friday. Within the warning area these showers and thunderstorms will be slow moving and may cause localised surface water impacts. Rainfall totals will vary considerably and not all locations will be affected by the heaviest showers.
"However, where the showers do occur there is potential for 20-30mm of rain in a short space of time and during the course of the day there is a chance that some places could see as much as 80-100mm build up.”
Several businesses and properties in Edinburgh were hit badly by extreme downpours causing flash floods across the city last month.
Parts of the new St James Quarter flooded and businesses in Stockbridge had to shut up shop temporarily until the rainfall eased.
Scottish Water also confirmed waste water and excrement could well have leaked into West Princes Street Gardens after the city’s sewerage network was “overwhelmed” during the extreme weather.