The State Emergency Service (SES) is advising people to remain vigilant and plan ahead for the expected wet weather forecast for northern parts of the state over the next 24 hours.
The Bureau of Meteorology issued a severe weather warning this morning for heavy rainfall across the Flinders Ranges and southern parts of the North East Pastoral districts, and the northern parts of the Mid North.
Rainfall and thunderstorms will increase across these areas from this afternoon, with totals of between 40 and 60 millimetres possible over a six-hour period, while 24-hourly totals to the end of Friday may reach 60-100mm.
This comes after an already wet month in this part of the state, with near saturated catchments.
A separate flood watch also remains current for these areas, including parts of the Riverland.
SES state duty officer Dave O'Shannessy said that motorists needed to closely monitor conditions and not drive through floodwater.
"With the state borders opening earlier this week we are already seeing more vehicles on the roads," he said.
"If you need to travel know the risk in the area you are travelling through, be on high alert for flooding, potholes and other hazards, slow down and drive to the conditions.
"Motorists should also be aware that floodwaters may rise rapidly and are likely to be fast moving."
He said it could take as little as 15 centimetres of floodwater for a vehicle to become unstable, lose traction and wash away.
Mr O'Shannessy said motorists should also watch out for large trees as recent wet and windy weather may have destabalised trees or branches, making them more likely to fall.