Dunedin astronomer Dr Ian Griffin said it was expected to create spectacular aurora australis across southern skies tonight, and he encouraged everyone to get out and take a look.
"The radiation storm, which is something that precedes the event, has been really, really strong all afternoon, and that's always a good sign.
"But the big question is, will it hold out until darkness in New Zealand.
"I think there's a really good chance we'll see something tonight in our sky.
"The forecast for Dunedin is quite cloudy, but inland, you might see something.
"Folks like myself, are getting quite excited, packing our cars with cameras and trying to head out and hopefully see something."
He said the storm hit Earth overnight in Europe, and his family members near London had sent him photos of "beautiful red and green skies" in the Northern Hemisphere.
"This is something that's impacting the whole Earth."
Another "strong X1.2 solar flare" with its own CME was launched from the Sun towards Earth earlier today, prompting alerts from Nasa, the National Oceanic and Atmospheric Administration, and New Zealand’s National Emergency Management Agency (Nema).
Dr Griffin said it meant more aurora may be visible across southern skies for the next few days.
"There's a bunch of incoming stuff.
"Obviously, the weather forecast for the next few nights isn't super great, so tonight might be the best chance to see something."
The colourful phenomenon is caused by charged particles from coronal mass ejections of plasma from the sun, when they collide with gases like oxygen and nitrogen in Earth's atmosphere.
It causes them to release energy in the form of light which creates the colourful displays over head.
The onset of the severe geomagnetic storm also has the potential to affect power transmission lines, so Transpower is keeping a close eye on the grid.
Sometimes, it will remove South Island electricity transmission lines from service to prevent damage to critical equipment.
Removing the circuits from service does not have any impact on consumers’ electricity supply.
Nema is monitoring the large ejections and believed they were unlikely to result in significant impacts to New Zealand’s electricity grid.
