There was flash flooding today after torrential rain hit the south coast.
Police in Dorset said the main area to be affected was Bournemouth, where a four-day air show is beginning today.
Vehicles, including buses, have broken down and roads have been closed due to the sudden downpour.
Residents have also reported drains lifting and water almost rising up to the bonnets of cars.
In Bournemouth town centre, Wessex Way was closed for a time because of flooding and traffic was diverted via The Triangle.
"Surface water does remain in areas and motorists are advised to proceed with caution and avoid making journeys if at all possible," a Dorset Police spokesman said.
"A number of roads are closed and a good deal of vehicles have broken down."
The force said parts of Wimborne Road, Wellington Road and Magna Road were blocked because of the rain and broken-down vehicles.
Exeter Road was closed after a wall collapsed - because of the floods - and ruptured a gas main, causing homes and businesses to be evacuated.
"It is Bournemouth town centre where the heaviest floods are being felt," the spokesman said.
"The latest information I have is that the rain is calming down and a lot of the surface water is starting to subside."