The solar cycle and the aurora

What the solar cycle is

The Sun's magnetic field gets more tangled over the course of the cycle, producing more sunspots, solar flares and coronal mass ejections (CMEs). At solar minimum there can be weeks without a single sunspot; at maximum there can be more than a hundred on the visible disc at once. Around maximum, the Sun's magnetic poles flip, and then activity gradually declines towards the next minimum.

The cycle is not perfectly regular. Cycles have lasted between about 9 and 14 years, and their strength varies a lot. Solar cycle 25 began in December 2019 and turned out to be stronger than most early forecasts expected.

How the cycle affects the aurora

• Around maximum, CMEs are frequent. They cause most of the biggest storms, the ones that bring aurora to places like southern England, central Europe or the southern United States.
• In the declining phase, large coronal holes often form at lower solar latitudes. They release fast solar wind streams that cause repeated moderate storms, often returning every 27 days as the Sun rotates.
• Big CMEs still happen in the declining phase. Several of the strongest storms on record occurred after solar maximum.
• At solar minimum, storms are rarer, but the aurora does not stop. Under the auroral oval, in Tromsø, Abisko, Fairbanks or Yellowknife, it is visible on many clear nights even at minimum.

Solar cycle 25 so far

Cycle 25 was particularly generous in 2024. On 10–11 May 2024 a series of CMEs produced the first G5 (extreme) storm since 2003, with aurora seen and photographed at unusually low latitudes on several continents. On 10–11 October 2024 another CME brought a G4 (severe) storm and widespread aurora across Europe and North America.

NASA and NOAA announced in October 2024 that the Sun had reached its maximum period, and the smoothed sunspot number appears to have peaked around late 2024. Activity has since started to decline slowly, but strong flares, CMEs and storms continued through 2025 and into 2026.

What to expect in 2026–2030

For aurora watchers, 2026 and 2027 should still be very good years. The declining phase typically brings frequent coronal-hole storms with good recurrence, plus occasional large CMEs. That means regular moderate displays in Scandinavia, Iceland, Scotland and Canada, and a reasonable chance of at least a few strong storms each year.

From around 2028 to 2030, activity should drop further towards the next minimum, expected around the end of the decade. Big storms will become rarer, but the auroral zone will still see displays on most clear, dark nights. If you want the best odds of seeing aurora far from the pole, the sooner the better; if you are travelling to the Arctic, any year can work.

Using the 27-day pattern

The Sun rotates once about every 27 days as seen from Earth. Long-lived coronal holes and active regions therefore tend to face Earth again about four weeks later, and a storm on one date is a useful hint that the following rotation may also be active. This is the main tool for rough aurora outlooks several weeks ahead.

The storm archive on this site lists past storms, so you can see which dates were active and look 27 days ahead. It is not a guarantee, as coronal holes change shape and fade, but it is better than guessing.

Seasons and the solar cycle

Within any year, geomagnetic storms are statistically more common in the weeks around the March and September equinoxes. At those times Earth's magnetic field is oriented in a way that couples more easily with the solar wind's southward field. Combined with the declining phase of the cycle, autumn and spring in 2026 and 2027 are especially good windows.

The total solar eclipse of 2 August 2027 offers a different view of the same active Sun: the corona, visible only during totality, shows the magnetic structures that drive space weather. The eclipse section of this site covers where and when to see it.

Frequently asked questions

Is it too late to see the aurora after solar maximum?

No. The declining phase of a solar cycle often brings frequent coronal-hole storms and still produces big CME-driven events. Under the auroral oval, in northern Scandinavia, Iceland, Canada and Alaska, the aurora is visible on many clear nights in every year of the cycle. 2026 and 2027 remain excellent years.

When was the peak of solar cycle 25?

The smoothed sunspot number appears to have peaked around late 2024, and NASA and NOAA announced in October 2024 that the Sun had entered its maximum period. Maximum is a period of a year or more rather than a single day, and high activity continued through 2025 and into 2026.

When is the next solar minimum?

The next minimum is expected around the end of the 2020s or the start of the 2030s, roughly 11 years after the previous minimum in December 2019. The exact timing will only be known in hindsight. Even at minimum, the aurora continues to appear regularly in the auroral zone.

What was the May 2024 storm?

On 10–11 May 2024 several CMEs from a large sunspot group hit Earth in quick succession, causing the first G5 extreme geomagnetic storm since October 2003. The aurora was seen and photographed far towards the equator in both hemispheres, including much of Europe, the United States, Australia and New Zealand.