The Peak of Solar Cycle 25

The Peak of Solar Cycle 25

The definitive peak—or “solar maximum”—of Solar Cycle 25 occurred in October 2024.

At its peak, the cycle reached a maximum smoothed sunspot number of roughly 161. The highest un-smoothed (raw) monthly sunspot count happened slightly earlier, in August 2024, hitting a count of 216.

Key Details About the Cycle 25 Maximum

• Beating Expectations: Solar Cycle 25 proved to be significantly more active than scientists originally forecasted. Back in 2019, the official Solar Cycle Prediction Panel projected a relatively mild cycle peaking around July 2025 with a maximum sunspot number of only 115.
• Arriving Early: Because the sun’s magnetic activity ramped up much faster and stronger than anticipated, the solar maximum arrived earlier than the initially predicted late-2025 window. NASA and NOAA officially confirmed the sun was in its peak maximum phase in mid-to-late 2024.
• How the Peak is Confirmed: The exact peak month of any solar cycle is always declared in hindsight. Astronomers calculate it using a 13-month “smoothed” sunspot average (which requires data from six months before and six months after a given month). Because of this formula, the true mathematical peak of October 2024 could only be definitively confirmed well into 2025 once solar activity had shown a consistent downward trend.
• The Downward Slope: While the sun has passed its primary peak, space weather events like solar flares and coronal mass ejections (CMEs) often remain elevated for a year or two following a maximum. Cycle 25 will now continue to gradually wind down, with the next solar minimum expected around 2030.