Smokey conditions in northern Adelaide

Changing weather conditions have pushed smoke from the Sampson Flat bushfire down to Adelaide's northern and outer northern suburbs.

The CFS says it expects smokey conditions for at least the next 24 hours.

CFS spokesman Russ Diggins says drivers need to take care and residents should keep windows and doors closed if possible.

Dozens of homes are likely to have been destroyed and at least 13 firefighters injured as South Australia's worst bushfire since the 1983 Ash Wednesday blaze continues to threaten lives.

The out-of-control Sampson Flat fire in the Mount Lofty Ranges is threatening 19 communities after travelling erratically and burning freely in all directions for most of Saturday.