The solar cycle: what the 2024 maximum means for the aurora now

The Sun swings between quiet and stormy periods in a cycle of roughly eleven years, measured by the number of sunspots. The current cycle, number 25, reached its maximum in October 2024, and by autumn 2026 we are well into the declining phase. That means fewer sunspots, but not the end of the aurora: strong storms can still happen, and in Northern Norway there is aurora on most clear, dark nights wherever we are in the cycle.

What the solar cycle is

Sunspots are dark, cooler patches on the Sun's surface where strong magnetic fields push up from inside. Around them sit active regions, which is where most solar eruptions and coronal mass ejections begin. The number of sunspots varies over a period of about 11 years, and the cycles have been numbered as they have been observed. The current one, cycle 25, began in December 2019.

According to NASA, the Sun's magnetic poles flip roughly every eleven years, around the top of the cycle. This magnetic switch drives the whole rhythm, from an almost spotless Sun at minimum to a Sun covered in active regions at maximum.

To see the long-term trend, scientists use a smoothed monthly sunspot number averaged over 13 months. It irons out the big swings from month to month, but it also means the peak can only be confirmed six months or more after the fact.

Cycle 25: stronger than expected

When an international panel of experts published its forecast in 2019, it expected a fairly modest cycle, with a maximum smoothed sunspot number of 105–125. That is not how it went. According to NOAA's data, the minimum came in December 2019 with a smoothed value of just 1.8. After that, activity rose faster than expected:

• The smoothed sunspot number peaked at 160.9 in October 2024. The Belgian sunspot data centre SILSO confirmed in 2025 that October 2024 was the maximum.
• The monthly value reached 216.0 in August 2024, the highest since September 2001.
• Cycle 25 thus ended up well above the previous cycle (116.4) but below cycle 23 (180.3).

NASA and NOAA announced on 15 October 2024 that the Sun had reached its maximum period, while stressing that the exact peak month could only be identified months or years later. It was also in 2024 that Europe saw the strongest geomagnetic storm in more than 20 years, in May, followed by another powerful storm in October. Read about them in our article on geomagnetic storms.

Where are we now, in autumn 2026?

The numbers are clearly falling. The latest available smoothed sunspot number, for March 2026, is 94.4, and the provisional monthly values have ranged between roughly 60 and 100 through 2026, with 60.3 in September. After confirming the maximum, the Belgian centre SIDC wrote that the Sun would remain very active well into 2026.

The declining phase usually lasts several years. When the next minimum will arrive is uncertain; a common estimate is around the end of the 2020s (unverified).

Storms in the declining phase

It is a common misconception that the aurora disappears once solar maximum is over. History says otherwise. According to the Belgian space weather centre STCE, the famous Halloween storms of 2003 came about two years after the cycle 23 maximum, and the strong storms of September 2017 about three and a half years after the cycle 24 maximum. Cycle 25 has already had a strong storm after its peak: on 12 November 2025 the disturbance reached level G4 (severe) on NOAA's scale.

Storms become rarer as the cycle heads towards minimum, but that takes years, not months. STCE notes that brief periods of very high activity can still occur over the next two to three years. The winters of 2026–27 and 2027–28 can therefore still bring powerful outbursts, even if they are unlikely to be as frequent as in 2024.

Coronal holes and the 27-day rhythm

In the declining phase another source of aurora becomes more important: coronal holes. These are regions on the Sun with an open magnetic field, where fast solar wind streams out (see solar wind, Bz and speed). NOAA writes that coronal holes are more common and longer-lived in the years around solar minimum, and that the most stable ones can last through several solar rotations.

Seen from Earth, the Sun turns roughly once every 27 days. A stable coronal hole therefore faces us again almost a month later. This creates a repeating pattern: if there was a good aurora 27 days ago because of fast solar wind, there is a fair chance of another window around the same time. Coronal hole streams usually cause minor to moderate storms (G1–G2), but they can last for days and bring several good evenings in a row. Every Monday NOAA issues a 27-day outlook of geomagnetic activity, which builds partly on this pattern. Treat it as a rough guide, not a precise forecast. See also how to read an aurora forecast.

What the cycle means for your aurora trip

• In Northern Norway the cycle matters less than many people think. You are under the auroral oval, where a clearly visible aurora occurs on more than half of all nights, even when the Sun is quiet. Weather and darkness are what decide.
• In southern Norway the cycle matters more. You depend on the oval being pushed south, which takes stronger activity, and that becomes rarer towards minimum. See the aurora in southern Norway.
• Strong storms keep coming for several years after maximum. Keep an eye on alerts about coronal mass ejections and on the Kp index.
• Planning: which months give the best odds, and why, is covered in our article on the best time of year.

In short

• The solar cycle lasts about 11 years. Cycle 25 peaked in October 2024 with a smoothed sunspot number of 160.9.
• We are now in the declining phase, but strong storms can keep coming for several years, as they did in 2003, 2017 and November 2025.
• Coronal holes create a 27-day pattern worth knowing about.
• In the north, clear skies and darkness matter most. Check tonight's verdict for your location.