A solar storm will sweep across the Earth Wednesday night, raising prospects of dazzling Northern Lights visible as far south as Chicago while prompting airlines and electric-grid operators to step up monitoring of the potentially damaging geomagnetic activity.

Solar eruptions—called coronal mass ejections—burst from the sun in two waves Monday and are building up enough energy to potentially become a level 3 geomagnetic storm when it hits, according to Rob Steenburgh, a space scientist with the U.S. Space Weather Prediction Center.

Solar storms, like hurricanes, are ranked on a five-step scale, with one being the weakest and five the strongest. Researchers won’t exactly know this storm’s strength until it reaches a monitoring satellite about 1 million miles (1.6 million kilometers) from Earth, at that point the waves will be about 90 minutes away and the forecast can be updated.

A G3 storm can trigger false alarms for protection devices in power grids, create drag on low-orbiting satellites and disrupt high-frequency radio traffic. In early February, Space X lost 40 Starlink satellites when they were launched into a geomagnetic storm. Airlines will have to monitor radiation levels, which could cause them to re-route polar routes. The storms could also interfere with birds, which sometimes causes havoc for pigeon racing, Steenburgh said.

Electric grids, for the most part, “won’t get jazzed up about a G3,” he said.

The sun goes through a 22-year cycle where it produces a lot of sunspots—the source of many storms—and then very few. It is currently moving toward the peak of its cycle. The sunspot region that caused the coming storms is actually shifting to the back of the sun now. But another area currently not visible did spark a large blast into space in the last day that was directed away from Earth.

“There is more activity working its way around,” Steenburgh said. “We are keeping an eye on things; this is one of many to come.”

Photograph: An M8.7 solar flare erupts from the sun accompanied by a large coronal mass ejection. Photo credit: NOAA.