Solar Cycle 25: The Sun Has Officially Reached the Peak of Its 11-Year Cycle

What Is a Solar Cycle?

Our mighty star—upon which we rely for light, heat, and energy—goes through warming and cooling cycles approximately every 11 years, which is largely tracked by the number of sunspots on its surface. 

Halfway through the 11-year cycle, the Sun’s activity grows very intense and stormy, leading to its peak or “solar maximum.” Think of the solar maximum as similar to the peak of a hurricane season (except that the Sun’s storms last a few years!).

So, at the solar maximum, the Sun’s magnetic poles flip! On Earth, that’d be like the North and South poles swapping places every decade or so.  Then, the Sun’s activity will begin to quiet down again until it reaches a “solar minimum” and starts a new 11-year cycle all over again.  Read more about solar cycles.

When Did Solar Cycle 25 Start?

We are now in Solar Cycle 25, which is the 25th cycle of the Sun, since recordkeeping began in 1755. (Galileo first observed sunspots in the 1600s.)

According to the Solar Cycle 25 Prediction Panel, an international group of experts co-sponsored by NASA and NOAA, Solar Cycle 25 began in December 2019.

• In 2019, 281 days went by without sunspots, the highest number of spotless days since 1913. Leading up to December, the Sun showed signs that its poles would reverse magnetic polarity.

At the end of December 2019, two reversed-polarity sunspots appeared. One sunspot in the Sun’s northern hemisphere and one in its southern hemisphere had magnetic orientations opposite from those in similar locations during the preceding Solar Cycle 24, indicating that Solar Cycle 25 had started. 

Solar Cycle’s Peak or Solar Maximum

On October 15th, NASA, the National Oceanic and Atmospheric Administration (NOAA), and the International Solar Cycle Prediction Panel announced that the Sun had reached its “solar maximum.” 

• Indeed, we are experiencing the greatest number of sunspots to date. Starting in early August 2024, sunspot counts had reached a 23-year high. 
• On October 3rd, 2024, Solar Cycle 24 released its strongest flare yet, an X9.0. (X-class flares are the strongest type of flare, and the number speaks to very high intensity.)

When Solar Cycle 25 began in 2019, scientists predicted that it would be a fairly weak to average cycle. Here is the forecast from 2019. The prior Solar Cycle 24 had been the weakest cycle in 100 years regarding sunspot activity. However, 

Solar Cycle 25 activity has exceeded expectations. It ramped up much faster than predicted, producing more sunspots and eruptions than had been forecasted. 

• By January 20, 2023, Solar Cycle 25 had already become bigger than Solar Cycle 24 had been at the same point in the cycle, with 12% more daily sunspots. 
• By October 2023, NOAA newly predicted a quicker, stronger solar cycle, with the peak coming by the end of 2024. One reason for this adjustment is that scientists have developed additional ways to track solar activity.
• In October 2024, NOAA and NASA theorized that the Sun had been in this cycle for about two years, given the high number of sunspots.

While sunspot counts are the main way to track solar cycle prediction, some researchers have also focused on tracking the magnetic activity that leads to sunspots—data that may lead to better forecasting.

That said, as San Diego State astronomer Douglas Leonard states, making a final call on the solar maximum dates is tricky. Perhaps sunspot counts will keep rising. While we may be experiencing solar maximum right now, “we won’t know for sure until we are about half a year beyond the peak and have enough post-peak data to indicate that it really was the peak.” 

The bottom line is that we can make our best guess, but determining the exact peak requires historical data so we can track a consistent decline in solar activity. The maximum is calculated by looking at the value of the six months prior and the six months following the solar maximum. Without the benefit of hindsight, there could be a false peak or some other pattern. 

When Will Solar Cycle 25 End and Solar Cycle 26 Begin?

Scientists anticipate that the maximum phase will last another year or so before sunspots begin to decline again. Solar Cycle 25 is predicted to end around 2030, with Solar Cycle 26 beginning in 2031. 

Interestingly, scientists announced that they already see the inklings of Solar Cycle 26, even while we’re halfway through the current cycle. This announcement is based on observing patterns on the Sun that have signaled the start of prior cycles. For example, sunspots and faster-moving material have started drifting toward the equator. 

Cycle 25 is not expected to end for another six years, but using helioseismic data to examine the Sun inside should reveal new insights into solar activity and timing!

Why Solar Activity Matters

One of the many reasons that scientists track solar cycles is the same as why we track weather and climate on Earth.

• The Old Farmer’s Almanac believes that the solar cycle and number of sunspots affects long-range weather here on Earth. The solar maximum in 2024–2025 would contribute to a milder winter forecast.
• Space weather can be destructive. Intense solar storms can disrupt satellite launches, cause radio blackouts, and effect astronauts. In modern times, it also affects GPS, navigation systems, and power grids on Earth.
• On the positive end, intense solar activity leads to a surge in electromagnetic energy hurtling towards the Earth and makes aurorae (Northern Lights) visible more often and at lower altitudes. 

Tracking Solar Activity

To keep track of Solar Cycle 25, see the NASA blog with monthly updates.

Teams at the Space Weather Prediction Center track solar activity and provide alerts in case Earth’s communications, satellites, power grids, and flight activity could be disrupted. To learn more, visit NOAA’s Space Weather Prediction Center.

As mentioned above, The Old Farmer’s Almanac’s famous long-range weather predictions have always considered solar science! Learn how the Almanac predicts the weather.