The Scottish Environment Protection Agency (Sepa) has 33 flood warnings, external in place.
Vincent Fitzsimons, Sepa’s flood duty manager, warned that flooding was expected across western coastal areas all weekend.
He said: “Impacts start in the Solway coast and Firth of Clyde on Saturday and then move around the coast to the eastern side of the country over the next few days.
“Of particular concern is likely impact to communities in the Western Isles and Orkney late Saturday and across Sunday.”
Mr Fitzsimons added the extreme conditions would also bring a storm surge and large waves.
He said this was a “particularly dangerous” combination, especially around high tides.
Mr Fitzsimons said: “There is real danger to life from wave overtopping, particularly around causeways, coastal roads and paths.
“Be careful when travelling around exposed coastal areas and don’t walk or drive through flood water as there may be hidden hazards.”