Geomagnetic Storm Watch Extended Through Saturday, Boosting Aurora Odds Over Northern U.S.

Forecasters at NOAA's Space Weather Prediction Center have kept a geomagnetic storm watch in effect through Saturday, raising the odds that the northern lights will be visible across a wide swath of the northern United States for a third straight night. The watch, one of the more sustained of the year, has been repeatedly extended as new bursts of solar material continue to arrive at Earth.

The activity traces back to an M6.9 solar flare that erupted from a sunspot cluster known as Active Region 4513, near the center of the visible solar disk, at 10:02 UTC on Aug. 25. The flare briefly disrupted high-frequency radio communication on the sunlit side of Earth, with effects reported across parts of Africa, Europe and the Arctic. It also launched a coronal mass ejection, or CME — a massive cloud of magnetized solar plasma — toward Earth, followed hours later by a second, smaller CME tied to a separate C4.7 flare and a filament eruption on the sun's surface.

NOAA's initial bulletin called for a G1, or minor, geomagnetic storm on Aug. 27 as a fast solar-wind stream from a coronal hole first reached Earth, stepping up to G2, or moderate, conditions on Aug. 28 once the CMEs arrived. In an updated advisory issued Aug. 26, the agency extended the G2 watch through Aug. 29, saying the combined disturbances were taking longer to fully clear than initially modeled.

Geomagnetic storms are ranked on a five-step NOAA scale from G1 to G5. A G2 storm sits toward the milder end of that range but can still produce measurable effects: voltage irregularities in high-latitude power grids, orientation and control complications for some satellites, increased atmospheric drag on spacecraft in low Earth orbit, and degraded high-frequency radio propagation at higher latitudes. None of those effects typically pose a direct risk to the public, and grid operators routinely monitor and compensate for storms of this magnitude.

The more visible consequence is aurora. NOAA's forecasts put the aurora oval — the ring-shaped region where the northern lights are most likely to be visible — far enough south that skywatchers in parts of Montana, North Dakota, northern Minnesota, the upper Peninsula of Michigan and northern New England have a strong chance of seeing displays after dark, with more moderate odds extending as far south as New York, Wisconsin and Washington state under clear, dark skies. Viewing chances are best late at night into the pre-dawn hours, away from city lights, and NOAA maintains a continuously updated 30-minute aurora forecast that skywatchers can check before heading outside.

Coverage of the event from Space.com and EarthSky noted that Active Region 4513 remained magnetically complex and turned further toward Earth-facing position in the days following the initial flare, meaning additional eruptions from the same region could extend elevated space-weather activity into the following week. Solar physicists have been watching for exactly this kind of behavior as the sun works through an active stretch of its roughly 11-year cycle, producing more frequent flares and CMEs than in quieter years.

For most people, the practical upshot of the watch is simply an unusually good chance to see the aurora without traveling to the Arctic. Photographers and skywatchers across the affected latitudes have already begun sharing images from the first two nights of the storm, and forecasters say conditions Saturday night should remain favorable before the geomagnetic activity is expected to gradually taper off early next week, assuming no further eruptions from the active region complicate the outlook.