Geomagnetic Storm Will Likely Reach U.S. September 24
A high-speed solar wind stream and coronal mass ejection will likely drive G1-class aurora displays.
Updated on Sept. 22, 2026 in Space
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Forecasters expect a solar wind event to trigger a G1 geomagnetic storm on September 24, 2026. This activity may extend the visibility of the Northern Lights across 22 U.S. states.
Why it matters
The interaction between solar particles and Earth's magnetic field creates auroras, while extreme space weather events pose significant risks to critical infrastructure. The potential economic impact of a solar superstorm is estimated at $2.4 trillion.
The Kp index, a measure of geomagnetic activity, is forecast to reach 5.33, signaling a G1-class event. This level occurs when solar wind interacts with the magnetosphere, specifically when the interplanetary magnetic field points south.
The details
The geomagnetic activity is driven by a combination of a coronal hole high-speed stream—a region in the sun's outer atmosphere where solar wind escapes rapidly—and a coronal mass ejection, which is a significant release of plasma and magnetic field from the sun. When these charged particles reach Earth, they enter the magnetosphere if the interplanetary magnetic field is oriented southward. This facilitates the acceleration of electrons into the upper atmosphere, causing the excitation of atoms that produce visible light emissions known as the aurora.
Timeline
September 23, 2026: Active conditions are expected by late in the day.
September 24, 2026: G1-class geomagnetic storms are likely during the early hours.
September 26, 2026: The moon reaches its full Harvest Moon phase.
The Tech Race
Current solar weather tracking focuses on refining models used to predict geomagnetic disruption, which is critical for protecting the global power grid. This G1 event follows ongoing efforts to monitor space weather against the historical benchmark of the 1859 Carrington Event.
Observers across 22 U.S. states, including Washington, Montana, Minnesota, and Maine, have the highest probability of seeing the aurora if skies are dark and clear. Viewers should note that the rising full Harvest Moon on September 26 may increase light pollution, potentially hindering visibility.
The takeaway
While G1 storms are routine, they provide a recurring opportunity to monitor the impact of solar activity on the upper atmosphere. Residents should track official NOAA updates for real-time adjustments to storm strength, which could potentially escalate to G2 levels.
Further reading
For more on the current understanding of space-based threats, see the latest research in Space.
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Is the U.S. adequately prepared to handle a major solar storm event?
