The event, called Coronal Mass Ejections, have sent 10 billion tonnes of superhot gas speeding towards the Earth.
"We predicted it would be a mid-level storm, a G-3, and that’s where it is," Joe Kunches, chief of space weather operations at the US-based National Oceanic and Atmospheric Administration's Space Environment Centre said.
A coronal mass ejection (CME) is an explosion of gas and charged particles into space from a solar flare in the Sun's corona.
The storm is expected to last through the weekend.
Electric utilities and other high-technology users were notified about the storm, but no serious problems have yet been reported.
"We have heard from the power grid operators. They are doing OK, but they are seeing the effects of the storm in their data," Kunches said.
During the storm the sun sends more energy than usual towards the Earth.
"The earth's magnetic field pulls it in… and is now trying to balance it," Kunches explained.
The effect can be felt worldwide. Scientists have warned the geomagnetic storm could affect power systems, communication and cell phones.