On the night of May 10, 2024, people in Florida, Texas, and northern Mexico looked up and saw the sky glowing red and green. It was the northern lights, visible at latitudes where most residents had never witnessed them. The geomagnetic storm behind that display was classified G5, the highest tier on NOAA’s scale, and the USGS Geomagnetism Program measured a peak Dst of -351 nT, making it the most intense magnetic disturbance since the Halloween Storms of October 2003.
That event may not have been a grand finale. A peer-reviewed study covering five consecutive solar cycles has found that the most extreme geomagnetic storms tend to cluster not during the sunspot peak but during the years of decline that follow. As of June 2026, the sun appears to be settling into exactly that declining phase, which means the window for spectacular auroras and serious space-weather risks is likely widening, not closing.
The statistical case for the declining phase
The core argument rests on a study published in Advances in Space Research by Vennerstrom, Lefevre, Dumbovic, and colleagues, who analyzed Dst index values and sunspot numbers across Solar Cycles 20 through 24, spanning roughly 1964 to 2019. The study was published in 2022. The Dst index is a direct measurement of how much Earth’s magnetic field is being compressed and distorted during a storm, recorded by ground-based magnetometers around the equator. Lower (more negative) values mean stronger storms.
What the researchers found was striking: geomagnetic storm rates were consistently elevated during the descending phases of all five cycles they examined. This held true across severity categories, including the most extreme events. The pattern was driven by a combination of fast coronal mass ejections and high-speed solar wind streams flowing from coronal holes, both of which remain active well after sunspot counts begin to fall.
The finding does not mean solar maximum produces no major storms. It means the declining years generate a disproportionate share of the strongest ones.
Where Solar Cycle 25 stands now
On October 15, 2024, a joint briefing by NASA, NOAA, and the international Solar Cycle Prediction Panel formally announced that Solar Cycle 25 had entered its solar-maximum period. A critical detail from that briefing: the precise peak month of any cycle can only be identified retroactively, after sunspot numbers show a sustained decline over many months.
The NOAA Space Weather Prediction Center’s solar cycle progression chart tracks observed sunspot numbers against the official forecast curve. As of mid-2026, the data suggest that sunspot activity has begun trending downward from the levels seen in 2024, consistent with the early stages of a declining phase. But the picture is not yet definitive. Several past cycles, including Cycle 24, exhibited double peaks separated by a year or more, with activity dropping and then surging again before the final descent. If Cycle 25 follows that pattern, the true onset of decline could be delayed.
NASA’s Solar Cycle 25 overview notes that this cycle has already exceeded the prediction panel’s initial sunspot-number forecast by a wide margin, adding another layer of unpredictability.
What the May 2024 storm revealed
The G5 event of May 10, 2024, gave scientists a detailed modern case study of an extreme storm occurring near the boundary between peak and decline. NOAA’s Space Weather Prediction Center described it as the strongest geomagnetic storm in more than two decades. GOES satellite data and ground-based neutron monitors confirmed the storm’s intensity across multiple instrument classes.
Whether that storm ultimately gets classified as a peak-phase or early-declining-phase event depends on where the eventual sunspot peak is placed once the full cycle is known. That distinction matters for future statistical analyses, but for practical purposes, the storm demonstrated that Solar Cycle 25 is capable of producing disturbances at the very top of the severity scale.
Auroras from the event were reported across the continental United States, parts of Central America, southern Europe, and even portions of the Southern Hemisphere. For millions of people, it was a once-in-a-lifetime sighting. If the declining-phase pattern holds, it may not be the last such opportunity this cycle.
The gaps that remain
The statistical study established a clear historical pattern, but it did not issue predictions specific to Solar Cycle 25. No published model attempts to forecast whether the same distribution will hold for this particular cycle, which has already behaved differently from what the prediction panel expected.
Direct statements from NASA or NOAA scientists explicitly linking the May 2024 storm to declining-phase dynamics are absent from the public record. The storm occurred while sunspot counts were still near their highest levels, making its phase classification ambiguous until the full cycle shape is known.
Systematic databases tracking auroral visibility at mid-latitudes across different cycle phases have not been published for the current cycle. Social media and news reports provide vivid accounts, but they lack the standardization needed for rigorous comparison. That makes it difficult to translate Dst statistics directly into predictions about how often people in, say, the central United States should expect to see the northern lights.
The physical drivers of extreme storms also vary from event to event. Some are dominated by fast, magnetically complex coronal mass ejections. Others are reinforced by persistent high-speed solar wind streams from coronal holes, which tend to become more prominent as the sun’s magnetic field reorganizes during the declining years. How that mix will evolve in Cycle 25 remains an open question.
Why the risk window for extreme auroras is still open
For power grid operators, satellite companies, and aviation planners, the practical implication is clear: the risk of severe geomagnetic storms did not peak and pass with the 2024 maximum. The statistical record across five solar cycles shows that the years after the sunspot peak tend to produce more of the strongest disturbances, not fewer. Mitigation plans, hardware protections, and operational protocols should be calibrated for several more years of elevated risk, not wound down.
For skywatchers, the outlook is genuinely encouraging. Historical patterns suggest that some of the most spectacular auroral displays of a solar cycle arrive after the headline “solar maximum” has come and gone. The May 2024 storm pushed the northern lights to latitudes where they are almost never seen. If the declining-phase pattern from cycles 20 through 24 repeats, similar opportunities could arise multiple times before Solar Cycle 25 bottoms out, likely sometime around 2030.
None of this amounts to a guarantee. Current forecasting tools cannot predict when the next G5 storm will strike, and the possibility of a double-peaked maximum means the cycle’s trajectory is still being written. But the weight of five decades of geomagnetic data points in one direction: the most dramatic chapter of Solar Cycle 25 may still be ahead.
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*This article was researched with the help of AI, with human editors creating the final content.
