The Scottish Environmental Protection Agency (SEPA) have added two severe “danger to life” flood warnings for the Aberdeenshire towns of Inverurie and Kintore.
Some evacuations have been advised.
A SEPA spokeswoman said: “In particular in Inverurie we are forecasting the embankment will have overspill and it could really catch people by surprise. If it comes over it will come over at a rate of knots.”
SEPA also have 37 separate flood warnings and eight flood alerts in Scotland.
Police are advising motorists in some areas to only travel if “essential”.
Meanwhile there is a snow and ice “be aware” yellow warning covering the Borders, Dumfries and Galloway, and parts of South Lanarkshire and East and South Ayrshire issued by the Met Office and in force until 9am on Friday.
The snowfall will be mainly over 200m, but may to fall to lower levels for a time.
The North East Scotland MSP and Scottish Liberal Democrat spokeswoman for Health and Justice, Alison McInnes called on “besieged” communities across north-east and central Scotland to be given greater assistance to cope with flooding.