Cape Town - Eskom said on Wednesday it will implement stage 1 load shedding from 17:00, which will likely continue until 22:00.
It said the power system was constrained but stable for most of the day, thus enabling Eskom to perform maintenance without the need for load shedding.
"However, due to increased electricity demand and a shortage of generation capacity due to power station units being on maintenance, Eskom will implement stage 1 load shedding from 17:00."
The utility warned that any unexpected changes on the vulnerable and constrained power system could lead to a change in the load shedding stage at short notice.
As the cold weather is contributing to the increased demand on the grid, Eskom urged electricity users to consider energy efficient ways of keeping warm.