A solar flare was headed for Earth but would only cause slight communication disturbances, the SA National Space Agency said on Friday.
Spokesperson Catherine Webster said the massive ejection of energy from the sun would likely impact Earth's magnetic field late on Saturday morning.
"The effects of a coronal mass ejection will not harm humans and other life forms on Earth, as we are protected by the Earth's magnetic field," she said.
"It can cause disturbances to our communication systems like global positioning systems, radio communications, cellphones and DSTV (satellite television)."
The space agency expected only minor disturbances at this stage, which could last the whole weekend.
It would continue to monitor the flare's impact.