The South African Weather Service issued an orange level 9 weather warning for Gauteng and the extreme western parts of Mpumalanga for Sunday.
SAWS said there was a medium likelihood of severe thunderstorms with heavy rain across the two provinces from early Sunday morning.
Rainfall of between 100mm to 150mm is predicted for both provinces which could result in widespread flooding, road and bridge damage, mudslides, rockfalls and dam wall breakages.