Dorset Police have said drivers are causing considerable problems by ignoring diversion signs and trying to find their own alternative routes.
Back roads through small villages - particularly around the A35 road closure - are causing motorists problems. These smaller roads are either flooded, covered in flood debris or too narrow to cope with the increased volume of traffic.
Diversion routes have been carefully devised to provide the safest and most appropriate alternative routes for all road users, and ignoring the diversions will cause further delay and disruption.
Police advise that roads will be re-opened as soon as they are safe and passable.
More top news
More than 150 boats are taking part in the World Pilot Gig Championships - the biggest in its 27 year history.
A minute's applause will take place during the Army-Navy rugby match in memory of Captain David Seath, who died during the marathon.
RNLI lifeguards will start patrolling beaches in the region this weekend as the 2016 summer season get underway.