Where Solar Cycle 25 Stands in 2026
The Sun runs on a roughly 11-year cycle of magnetic activity, and the current one, Solar Cycle 25, has already passed its peak. The maximum came in October 2024, when the 13-month smoothed sunspot number reached 160.9 — well above cycle 24’s peak of 116.4 in April 2014, and earlier and stronger than the 2019 NOAA-NASA prediction panel’s forecast of 115 in July 2025. Since then the smoothed number has fallen almost every month, to 99.8 by February 2026, and there has been no second peak. August 2026 averaged a sunspot number of 76 on the provisional count, and NOAA’s current prediction puts the smoothed figure near 90 this autumn.
Around solar maximum the Sun produces more solar flares and coronal mass ejections (CMEs). These travel 150 million kilometres to Earth, where they disturb the planet’s magnetic field and funnel charged particles toward the poles. The result is the aurora borealis. But the number that matters for the aurora is not the sunspot count; it is geomagnetic activity, and in 2026 that has held up much better than the sunspots have.
The first eight months of 2026 averaged a planetary ap index of 12.6, above the same months of 2024 (11.1), the year the sunspots peaked, though below 2025 (15.2). Of the last twenty years, only 2025 had a more active January to August. By the standard of the full record, which GFZ Potsdam keeps back to 1932, that is an ordinary figure — the long-run median for those months is 12.5 — but it is higher than any year of the weaker cycle before this one.
What Solar Cycle 25 Has Already Delivered
Solar Cycle 25 has already proven more intense than the prediction panel expected. In May 2024, Earth experienced a G5-class geomagnetic storm, the first time the planetary Kp index had reached 9 since October 2003, which produced auroras visible across large parts of North America and Europe. Kp has reached 9- three times since — in October 2024, November 2025 and January 2026 — each a G4 storm.
For Iceland, storms of this magnitude mean full-sky aurora displays that extend well past midnight, with vivid curtains of green and sometimes red or purple light visible even from Reykjavik’s outskirts. Locations with darker skies — such as Þingvellir National Park or Kirkjufell Mountain — benefit even more, with the full structure of coronal arcs and dancing rays visible to the naked eye.
Why the Declining Phase Still Produces Strong Auroras
A common misconception is that once solar maximum has passed, aurora activity drops off sharply. It does not, at least not straight away. As the cycle declines, large coronal holes open on the Sun and send streams of fast solar wind past Earth, returning every 27 days as the Sun rotates, and big eruptions still happen: some of the strongest flares and storms of recent cycles came years after sunspot maximum.
The pattern shows up in the geomagnetic record. Solar Cycle 23’s sunspots peaked in November 2001, but its most geomagnetically active year was 2003, the year of the famous Halloween Storms. Cycle 24’s sunspots peaked in April 2014, and its most active year was 2015. Cycle 25’s sunspots peaked in October 2024, and so far its most active year has been 2025.
So 2026 is neither a last chance nor a peak. NOAA’s current prediction has the smoothed sunspot number falling from about 90 this autumn to single figures by the end of 2030, and storms will very likely keep coming as the cycle declines, if less often. If the next cycle runs to a typical length, its maximum will fall in the mid-2030s.
How to Translate Solar Activity Into an Aurora Forecast
Understanding the solar cycle is useful context, but planning a specific night’s aurora viewing requires real-time data. Three measurements matter most:
- Kp index: A 0–9 scale measuring global geomagnetic disturbance. A Kp of 3 or above produces visible auroras in Iceland; Kp 5 and higher produces dramatic displays across the whole sky.
- Bz component: The north-south orientation of the solar wind’s magnetic field. A strongly negative Bz (below −10 nT) opens the Earth’s magnetosphere and dramatically amplifies aurora activity.
- Cloud cover: Iceland’s weather is the variable you cannot control. Clear skies over your location — not just low Kp — determine whether you see anything.
The live aurora forecast in the Aurora Iceland app combines all three in real time, scoring each viewing spot on a 0–100 scale based on OVATION aurora probability, actual cloud cover, and local darkness. During elevated solar activity, checking this forecast an hour before heading out can save a wasted drive — or reveal that the skies directly above Jökulsárlón Glacier Lagoon are clearing while Reykjavik stays overcast.
Practical Advice for the 2026 Season
Iceland’s aurora season runs from late August to mid-April, constrained by the need for genuine darkness. The summer months bring the midnight sun and no auroras at all; the winter months offer the longest dark windows. April sits at the tail end of the season — twilight grows longer each week, but strong geomagnetic events can still produce visible auroras on clear nights through mid-April.
If you are planning a trip around the solar cycle, September through March gives you the dark nights. The months around the equinoxes are particularly favourable: in the planetary Kp record, storm-level periods — NOAA G1 or stronger — are about twice as common in March, April, September and October as in the months around the solstices, a pattern known as the Russell-McPherron effect. The average level of activity moves far less, so what the equinox adds is mostly strong nights. Cloud, on the other hand, barely changes with the season in Iceland, so no month gets you out of chasing clear sky.
For maximum flexibility, choose accommodation in the countryside rather than Reykjavik. Light pollution is the one factor you can control directly — moving even 30 kilometres from the city makes a measurable difference on nights when activity is moderate rather than exceptional.
Make the Most of the Declining Phase
Solar Cycle 25 has already produced aurora events that people in Iceland will remember for years, and it is not finished. The honest case for a trip in the 2026-27 season is not that the Sun is at its peak — it isn’t — but that geomagnetic activity has held up better than the sunspots, and that the dark months still bring storms. What decides your trip is the same as in any year: dark nights, clear sky, and being ready to move.
Download the Aurora Iceland app to get real-time scores for 137 viewing spots across Iceland, or check the Tonight page for the current forecast at your location. When the Kp index climbs and the clouds part, you will want to move quickly — and having the data in your pocket makes all the difference.