The National Oceanic and Atmospheric Administration issued a severe northern lights alert for much of Canada and the northern U.S. this week.
This alert warns of potential visibility of the aurora borealis for millions of residents, marking a significant increase in geomagnetic activity that can impact satellite communications and power grids.
The alert follows the eruption of three massive solar flares [9]. These flares are expected to trigger a G1 geomagnetic storm [7, 8], which creates the atmospheric conditions necessary for the northern lights to appear further south than usual.
Visibility is forecasted to occur overnight Thursday, June 4, through Friday, June 5, 2026 [6]. While some reports suggest the aurora may be visible in as few as 17 states [5], other data indicates up to 23 states [1, 2, 3], or even 25 states [4], could witness the phenomenon.
Observers in the northern U.S. and Canada are advised to look toward the northern horizon during the specified window. The varying estimates on the number of affected states reflect the unpredictable nature of geomagnetic storm boundaries, though the G1 classification remains the consistent baseline for the event's severity [7, 8].
NOAA monitors these solar events to provide advance warning for infrastructure operators and the public. A G1 storm is generally considered a minor storm, but it can still produce vivid auroral displays in higher latitudes.
“A forecasted G1 geomagnetic storm may make the aurora borealis visible across 23 U.S. states”
The discrepancy in the number of affected states, ranging from 17 to 25, highlights the volatility of solar wind interactions with Earth's magnetic field. While a G1 storm is the lowest level of geomagnetic storm, the presence of three massive solar flares suggests a concentrated burst of energy that can push the auroral oval further south, making the lights visible to populations that rarely see them.
