The yellow warning is in place until 9am on Tuesday (October 20).
Rain will continue moving north across Scotland this morning.
Later on Tuesday, more patchy and blustery rain will push northwards.
In the south, it will be drier with sunny spells – but a few showers will persist in the west.
Over hills and mountains, 50-75mm of rainfall is expected, according to the Met Office.
But some isolated spots including Argyll in Scotland could have as much as 75-100mm of rainfall.
ScotRail has reported flooding between Saltcoats and Ardrossan.
For safety reasons, trains for Largs and Ardrossan will only run as far as Kilwinning until the water level drops to a more suitable level.