Major 'Cannibal' Solar Storm Expected to Bring Northern Lights and Possible Power Disruptions to 18 U.S. States

A major solar storm formed by two merged coronal mass ejections is expected to strike Earth's magnetic field overnight, potentially producing wide-ranging auroral displays across 18 U.S. states and raising concerns about power grid and communications disruptions.

Space weather forecasters described the event as a "cannibal" storm — a stronger blast that forms when a later, faster cloud of charged solar particles overtakes and merges with an earlier one. That interaction can amplify the impact on Earth's magnetosphere and increase the intensity of a resulting geomagnetic storm.

Forecasters said the storm has a chance to reach G3, classified as "strong" on the NOAA G-scale, during the overnight hours into early Tuesday. There is a smaller probability that the event could briefly escalate to G4, considered "severe." At G3 levels, geomagnetic activity can cause voltage irregularities on power grids, create increased wear on transformers and raise the risk of localized outages. A G4 event would elevate those risks and potentially produce more significant impacts on high-latitude grid infrastructure.

Beyond effects on electricity networks, geomagnetic storms can interfere with high-frequency radio communications, perturb GPS positioning signals, and increase drag on low-Earth-orbit satellites. Operators of critical infrastructure and satellite services routinely monitor space weather alerts to take protective actions when solar activity intensifies.

The aurora is expected to be visible across much of the northern tier of the United States if skies are clear. States listed as likely to see the Northern Lights include Alaska, Montana, North Dakota, Minnesota, Wisconsin, Michigan, New York, Maine, New Hampshire, Vermont and Washington. Observers farther south may also see auroras in Idaho, Illinois, Iowa, Nebraska, Oregon, South Dakota and Wyoming during the peak of the storm.

Visibility will depend on local weather, light pollution and the storm's exact strength and timing. Skywatchers generally have the best chance of seeing auroras after local midnight and toward the hours just before dawn, when geomagnetic activity from a solar impact is most likely to peak.

Major geomagnetic storms have demonstrated real-world impacts in the past. A severe storm in March 1989 knocked out power across large portions of Quebec, underscoring how intense solar activity can translate into terrestrial outages. Space weather forecasters use that historical context when advising utilities, aviation operators and satellite controllers to implement mitigation steps during elevated alerts.

Emergency managers and energy companies monitor forecasts and often take preemptive measures, such as adjusting transformer loads or reconfiguring networks, to limit damage during strong geomagnetic activity. Individuals can reduce risk by keeping electronic backups charged, noting that short-term GPS or radio disruptions are possible during peak activity.

Forecasters continue to update the expected arrival time and intensity as the merged cloud approaches. Authorities advise those interested in viewing auroras to check local space weather reports and weather conditions and to follow guidance from utility providers and communications operators in the event of service disruptions.