Flood warnings are in place right across the west of England and Wales today.
After six weeks of wet weather, forecasters say the ground is now so wet in many areas any extra water will run off straight into rivers.
Rivers in Cumbria, Wales and Gloucestershire have risen to critical levels, the Environment Agency said.
Torrential rain in Scotland this week has resulted in the closure of schools,roads and public transport, and dozens have been forced to leave their homes.
Up to 240mm of rain has fallen in Glasgow so far this month - more than double December's average.
There are currently eight floodwarnings in place for England and Wales, but these would drop off as the rain began to clear.