Earth is taking a direct hit from a G2 geomagnetic storm as of May 15, 2026, and the northern lights are pushing far enough south that residents in as many as 20 states could see them tonight. The culprit: a gaping coronal hole on the sun’s surface, now rotated squarely toward Earth, firing a river of charged particles straight at the planet at hundreds of miles per second.
NOAA’s Space Weather Prediction Center, the federal agency that issues space weather alerts to power-grid operators, airlines, and satellite controllers, confirmed in its forecast discussion that “G2 (Moderate) storming conditions are likely on 15 May” and that elevated geomagnetic activity should persist through May 17. This is not a flash-in-the-pan event. It is a multi-day window of disturbed conditions, with tonight offering the strongest odds for aurora at mid-latitudes.
What is driving the storm
The engine behind this storm is a negative-polarity coronal hole, a region on the sun where magnetic field lines peel open and allow solar wind to escape at high speed. NOAA’s solar synoptic map shows the hole’s open field lines extending outward along the Sun-Earth line, the exact orientation that channels the fastest, densest solar wind toward our planet.
Before that high-speed stream reaches Earth in full, it slams into slower solar wind already drifting through interplanetary space. The collision creates what forecasters call a corotating interaction region, or CIR, a compressed shock front that amplifies the magnetic energy carried by the solar wind. It is that CIR impact that triggered the current G2 conditions, and the high-speed stream trailing behind it will keep feeding energy into Earth’s magnetosphere for the next two days.
This kind of storm is characteristic of the current phase of Solar Cycle 25. While the cycle’s sunspot activity has been running well above early predictions, coronal-hole-driven storms like this one are a recurring feature, especially as the sun transitions through and beyond solar maximum. They lack the drama of a coronal mass ejection but can produce sustained geomagnetic disturbances that last longer than many CME-driven events.
The numbers behind the forecast
NOAA’s three-day geomagnetic forecast spells out the trajectory. Predicted Ap index values, which measure average planetary magnetic disturbance over 24 hours, are 030 for May 15, 024 for May 16, and 019 for May 17. An Ap of 030 falls in the active-to-minor-storm range, consistent with G2 conditions. The maximum predicted Kp value for the period is 5.67, which on NOAA’s scale corresponds to G2 (Moderate).
For aurora watchers, the Kp number is the one that matters most. Values above 5 are the threshold at which the northern lights can become visible at mid-latitudes in the United States, particularly under dark, clear skies away from city light pollution. During the historic G5 storm of May 2024, Kp values soared past 9 and aurora appeared as far south as Florida and Texas. A G2 event will not produce anything close to that spectacle, but it can deliver a visible green or pink glow along the northern horizon for observers in the right locations.
Where the aurora could appear tonight
NOAA’s OVATION aurora model, which integrates real-time satellite data to generate rolling 30-minute probability maps, currently shows the auroral oval stretching far enough south to cover portions of states from Washington and Oregon across to Maine and down through the upper Midwest. That footprint is how the roughly 20-state estimate is derived, though the number shifts with each model refresh as real-time solar wind conditions evolve.
States with the strongest odds include Montana, North Dakota, Minnesota, Wisconsin, Michigan, Vermont, New Hampshire, and Maine. Observers in those areas, especially in rural locations with unobstructed northern horizons, have a realistic shot at seeing distinct auroral structures: green bands, faint curtains, or the telltale glow that photographs often capture better than the naked eye.
States on the southern fringe of the viewing zone, places like Iowa, Pennsylvania, Oregon, and possibly northern Illinois, face a narrower window. Visible aurora there depends on whether the Kp index spikes above 6 for at least a few consecutive hours, something that is plausible but not guaranteed by current forecasts. A secondary Kp spike during the early hours of May 16, when Earth’s nightside rotates more directly into the solar-wind stream, could briefly push the aurora a degree or so farther south.
What could change
Geomagnetic forecasts are inherently fluid. The single biggest variable is the orientation of the interplanetary magnetic field, or IMF, carried by the incoming solar wind. If the IMF tilts sharply southward, it couples more efficiently with Earth’s magnetosphere and the storm could briefly intensify beyond G2. If it stays mostly northward, the aurora display could fizzle for viewers in the lower 48, remaining confined to Canada and the far northern fringe of the U.S.
The declining Ap values across the three-day forecast suggest the storm will weaken steadily as Earth moves past the most compressed portion of the CIR and into the more uniform high-speed stream. But coronal-hole streams are notoriously variable, and minor fluctuations in solar-wind density or magnetic field strength can produce unexpected substorms on the nightside.
Weather is the other wildcard. Even under a strong G2 event, thick clouds will completely block the view, and a bright moon can wash out faint auroral structures near the horizon. Two towns at the same latitude can have completely different experiences of the same storm depending on local sky conditions.
Impacts beyond the light show
G2 storms sit at the moderate level on NOAA’s five-tier geomagnetic storm scale. At this intensity, power-grid operators may observe minor voltage irregularities, high-frequency radio propagation can degrade, and satellites in low Earth orbit experience slightly increased atmospheric drag. No utility operators have issued public statements about disruptions tied to this specific event, and widespread infrastructure problems at the G2 level are uncommon.
GPS-dependent systems and precision agriculture equipment may see brief signal degradation, particularly at high latitudes. Satellite operators typically monitor these conditions in real time and can make orbital adjustments if drag increases beyond expected margins.
How to watch tonight
The best viewing window typically falls between 10 p.m. and 2 a.m. local time, when the sky is darkest and nightside geomagnetic activity tends to peak. Find a location away from city lights with a clear, unobstructed view to the north. Give your eyes at least 20 minutes to adjust to the darkness, and avoid looking at bright phone screens during that time.
Scan the entire northern half of the sky rather than fixating on one spot. Faint aurora often appears first as a pale greenish-white arc low on the horizon, easy to mistake for distant light pollution. A smartphone camera set to night mode or a long exposure of a few seconds can pick up colors and structures the naked eye misses, so even if the sky looks quiet, it is worth taking a test shot toward the north.
NOAA’s OVATION model updates every 30 minutes and is the closest thing to an official “where can I see the aurora right now” tool. Check it after sunset for the most current probability map. The forecast discussion and three-day outlook, both linked above, provide the broader context for how the storm is expected to evolve overnight and into May 16.
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*This article was researched with the help of AI, with human editors creating the final content.
