Flood alerts have been put out and Strathclyde Police issued a warning to drivers about the dangers of speeding during adverse weather.
It came after two motorists were stopped for allegedly driving at around 100mph on the M8 on Wednesday night during what police described as extremely poor conditions.
The Met Office has amber "be prepared" weather warnings in place for central Scotland while yellow "be aware" warnings cover much of the rest of the country.
Wet weather is also causing trouble south of the Border, with southern and south western England, south east Wales, the Midlands and the north east of England the areas most at risk of flooding.
Nearly one inch of rainfall fell on Glasgow during Thursday with a further inch expected overnight. And the wet weather is predicted to continue until Christmas Day.
Matt Dobson, a forecaster with Meteogroup, said: "Heavy rain is sweeping from south to north and in Glasgow rainfall will easily get up to nearly an inch overnight.
"We're looking at a very wet weekend into Christmas Eve with heavy rainfall continuing on Christmas Day."
The wet weather forecast comes as drivers were warned to take care on the roads in "challenging" conditions
Police officers stopped two drivers on the westbound M8 between junctions 13 and 16 allegedly going at speeds of 98mph and more than 100mph in a 50mph zone. Superintendent Jim Baird said: "If you drive in excess of the speed limit you risk not just your life, but other road users' lives also. To do so in such poor weather and road conditions is just plain dangerous and is unacceptable."
Meanwhile, flood alerts have been issued for coastal areas still recovering from severe weekend storms.
Weather warnings are in place across Scotland with police cautioning drivers about a build-up of surface water on roads across Angus, Dundee and Perth and Kinross.
Ports and flood defences were damaged in Aberdeenshire and Berwick and 60 people evacuated from homes in Stonehaven and Peterhead.
In England, residents in about 25 homes in the Hampshire village of Wallington had been offered the chance to evacuate by police amid fears that the River Wallington could burst its banks. But the majority elected to stay put at the moment because river levels were dropping.