Snow and ice could follow heavy downpours which have left parts of the UK waterlogged as forecasters warned of a return to freezing temperatures.
A deluge of rain saw areas including Cumbria flooding on Tuesday and more than a dozen flood warnings remain in place for parts of north-west, north-east and south-west England and Wales.
The Met Office has issued yellow warnings for rain across much of the country on Wednesday as the tail end of the US Storm Jonas continued to sweep in from the Atlantic.
On top of the flood warnings, which advise that "flooding is expected" with "immediate action required", the Environment Agency (EA) has issued a further 115 amber alerts to communities in the north, west and south of England, Wales and Scotland to expect flooding.
And experts warned that the falling mercury could mean a risk of icy patches in places such as Cumbria and Lancashire, which are saturated by rain water.
Paul Mott, a forecaster for MeteoGroup, said rainfall was not expected to be as high as on Tuesday, when up to 100mm (3.9ins) fell in northern areas.
He added that temperatures could briefly drop to around zero before rebounding later in the week.
Troops were put on standby and the EA deployed temporary defences and pumps in preparation for further flooding, from which some communities are still reeling following the storms last month.
Pictures and videos posted on social media by Cumbria residents on Tuesday afternoon showed heavy rain and blocked roads. Local police forces have urged drivers and people walking near the coast to take care, while a handful of schools closed.
The county council said they were all expected to reopen today.
In Scotland, pupils and staff at a primary school in Stirling had to be evacuated by boat after the building was cut off by flooding.