“For most people here on planet Earth, they won’t have to do anything,” said Rob Steenburgh, a scientist with NOAA’s Space Weather Prediction Centre.

The storm could produce northern lights as far south in the US as Alabama and Northern California, NOAA said. But it was hard to predict and experts stressed it would not be the dramatic curtains of color normally associated with the northern lights, but more like splashes of greenish hues.

“That’s really the gift from space weather: the aurora,” Mr Steenburgh said. He and his colleagues said the best aurora views may come from phone cameras, which are better at capturing light than the naked eye.

Snap a picture of the sky and “there might be actually a nice little treat there for you,” said Mike Bettwy, operations chief for the prediction centre.

The most intense solar storm in recorded history, in 1859, prompted auroras in central America and possibly even Hawaii. “We are not anticipating that” but it could come close, Shawn Dahl, the NOAA space weather forecaster said.

This storm poses a risk for high-voltage transmission lines for power grids, not the electrical lines ordinarily found in people’s homes, Mr Dahl told reporters. Satellites also could be affected, which in turn could disrupt navigation and communication services here on Earth.

An extreme geomagnetic storm in 2003, for example, took out power in Sweden and damaged power transformers in South Africa.