Eskom will start with stage 1 load shedding at 17:00 on Saturday. The cuts are expected to last until 22:00.
The power utility will also cut power during the same hours on Sunday afternoon.
On Friday, Eskom said that although it had made some progress in replenishing the emergency generation reserves of water and diesel, it still needed to institute rotational power cuts over the weekend.
"Eskom would like to remind the public that these capacity constraints will continue for the foreseeable future, and all South Africans are urged to reduce their use of electricity, particularly between 17:00 and 22:00, when the winter demand is the highest," it said.
"The supply outlook for the coming week is expected to improve as additional generation units are planned to return to service. Eskom will promptly inform the public should there be any significant changes."