CME-Driven Aurora Forecast: Northern Lights in U.S.

A coronal mass ejection (CME) that erupted from the Sun on 26 June is forecast to strike Earth on the night of 29 June. NOAA’s Space Weather Prediction Center projects a Kp index of 5 (out of 9), indicating a G1 geomagnetic storm that could extend the aurora into the northern United States.

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CMEs are massive plasma and magnetic field bursts traveling up to 1,900 mph, reaching Earth in days. Interaction with Earth’s magnetosphere triggers geomagnetic storms, measured by the Kp index (0-9) and classified from G1 to G5. Aurora visibility expands southward when Kp reaches 4-5 under dark skies.

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NOAA predicts Kp 5 and a G1 storm; UK Met Office notes a possible G2 escalation. Highest likelihood states are Washington, Idaho, Montana, North Dakota, South Dakota, Minnesota, Wisconsin, Michigan and Maine. Alaska falls in a “high” zone, and faint aurora may appear in Oregon, Wyoming, Nebraska, Iowa, Illinois, Indiana, Ohio, New York, Vermont and New Hampshire.

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NOAA’s Space Weather Prediction Center warned that conditions are expected to return to mid on 30 June due to CME that left Sun on 26 June. The agency advises travelers to seek dark northern horizons and avoid light pollution. The UK Met Office indicated that CME’s arrival on day three could raise activity to G1 minor storms with a chance of G2 moderate storms, and that risk may persist into 1 July. SpaceWeather.com issued alerts tracking CME’s progress.

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NOAA assigns a “low” likelihood to most border states, yet a Forbes analysis lists up to 19 states—including mid-latitude locations—where aurora could be seen. NOAA forecasts only a G1 storm; UK Met Office mentions a possible G2 moderate storm. Astronomers warn that full Strawberry Moon and cloud cover will brighten the sky, reducing visibility. Neither source provides real-time cloud data, leaving a key factor unaddressed.

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• “Enhanced conditions are expected to return early to mid on 30 Jun due to the CME that left the Sun late on 26 Jun.” — NOAA Space Weather Prediction Center

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• “CME arrival on day 3 is expected to increase activity to Active to G1 Minor Storms with a chance of G2 Moderate Storms,” — UK Met Office Space Weather forecast

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• “NOAA is predicting a Kp index of five out nine for Monday night, meaning the aurora could appear brighter and further south from the magnetic north pole.” — NOAA

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• “The lights also have a decent chance to be visible from Alaska, with most of the state falling within the “high” likelihood for visibility area on Monday night.” — NOAA

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Space-weather forecasters will issue daily updates through July 1, and observers are urged to monitor NOAA’s alerts and local cloud forecasts for optimal viewing.

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