Cape Town - Eskom announced on Tuesday that it will implement stage 1 load shedding from 17:00, which will likely last until 22:00.
Eskom warned earlier on Tuesday that chances of load shedding were low for the morning, but high for the evening.
The utility started load shedding again on Sunday evening after ten consecutive days of no load shedding, as it struggles to meet the increased winter demand for electricity.
On Monday Eskom moved quickly from stage 1 to stage 2 "due to a further shortage of generation capacity".
Eskom said in winter the electricity demand peaks in the morning and evening as more electricity is used during these times. It appealed to customers to continue to reduce their electricity usage throughout the day, but to be aware of the need to save more during the peak periods from 06:00 to 10:00 and 17:00 to 21:00.
"Any unexpected changes on the vulnerable and constrained power system could lead to a change in the load shedding stage at short notice," Eskom warned in a statement on Tuesday.
Check your load shedding schedules on GridWatch.
"As we are currently experiencing cold weather conditions across the country, we urge electricity users to consider energy efficient ways of keeping warm," Eskom said.
Meanwhile, official figures show that electricity generation (production) decreased by 4.7% year-on-year in April 2015, while electricity distribution (consumption) decreased by 2.4% year-on-year in April 2015.
Stats SA said on Friday seasonally adjusted electricity generation decreased by 2.5% in April 2015 compared with March 2015. This followed month-on-month changes of 0.8% in March 2015 and -0.8% in February 2015.
Seasonally adjusted electricity generation decreased by 0.6% in the three months ended April 2015 compared with the previous three months.
Seasonally adjusted electricity distribution decreased by 1.8% month-on-month in April 2015, following month-on-month changes of 1.1% in March 2015 and -0.4% in February 2015. Seasonally adjusted electricity distribution increased by 0.1% in the three months ended April 2015 compared with the previous three months.
Eskom said load shedding is implemented only as a necessary measure to protect the power system and to ensure that maintenance is carried out to guarantee that its supply of electricity can be maintained in the long term.