It happened on the hottest day of the year with temperatures soaring to 30 degrees across the area.
Although it happened near to Lochside Park, few witnesses saw the car career off the Castle Douglas-Gelston Road and plunge through grass and bushes, which were ten feet high.
The alarm was raised by a passing motorist and people in nearby houses and firefighters from Castle Douglas were called to the crash.
The woman, who is believed to be in her 30s, was helped from the car by police and firefighters and she was treated for shock and bruising by ambulance personnel.
A police spokesman said: “It was lucky that the car stopped where it did. The woman was helped from the vehicle and then taken by ambulance to Dumfries and Galloway Royal Infirmary at Dumfries 16 miles away.”
It is not thought she was badly injured.