Emergency services and staff from Bournemouth Christchurch and Poole (BCP) Council are helping residents at Iford Bridge Home Park who were told to pack an overnight bag and move pets and vehicles to safety.
Ron Curtis, from the Environment Agency, told the BBC residents should be allowed back soon once the situation improves.
Dorset Council said its crews had worked through the night, “clearing debris and tackling the highest‑risk spots”.
In a Facebook post, external it said it had also sent out its gritters as temperatures dropped and wet road surfaces turned to ice.
“Since the flooding began, our teams have worked through the night and day dealing with more than 200 call-outs,” the authority said.
There have been multiple incidents across the two counties, with drivers having to be rescued after getting stuck in flood water.
In the New Forest, a driver died when his lorry left the road in North Gorley and went into a river.