Forecasters are warning of more flooding tonight and tomorrow, with an amber weather warning - the highest level of alert - issued this morning
The warning has been upgraded from a yellow alert, with up to 40mm of rain 'likely' and up to 60mm possible. Most of the rain will fall in a six hour window, the Met Office says, increasing the risk of flash-flooding.
Given that the ground is already saturated in many areas with rain falling steadily so far all day today, the public should be aware of the risk of flooding, the warning says.
Parts of Poole and Christchurch and Wareham found themselves underwater last week after a similar band of heavy rain. Swanage high street was cordoned off for public safety.
Friday is expected to be showery but brighter, before a third wave of heavy rain arrives on Saturday morning.
This is expected to concentrate mainly on Devon and Cornwall, with only the western edges of Dorset covered by the weather warning, but where it does rain, surface water and flash floods are likely.
Saturday is expected to be the heaviest day on the roads as people make their way home for Christmas.