Another month has passed, and so it is time for my monthly update on the never-ending sunspot cycle on the Sun. using NOAA’s own monthly update of its graph of sunspot activity and annotating it with extra information to illustrate the larger scientific context.

The green dot on the graph below indicates the level of sunspot activity on the Sun’s Earth-facing hemisphere during the month of October. Not only did the number of sunspots decline from the count in the previous month, as predicted in April 2025 by NOAA’s panel of solar scientists (as indicated by the purple/magenta line), it dropped below their prediction.


The graph above has been modified to show the predictions of the solar science community for both the previous solar maximum as well as the ongoing maximum. The green curves show the community’s two original predictions from April 2007 for the previous maximum, with half the scientists predicting a very strong maximum and half predicting a weak one. The blue curve is their revised May 2009 prediction. The red curve is the new prediction, first posted by NOAA in April 2020. At the beginning of April 2025 NOAA’s panel of solar scientists added the purple/magenta curve line, predicting that solar maximum was over, and that the ramp down to minimum had begun

Ironically, October’s numbers were only the second time during this entire solar cycle that the sunspot count actually matched the April 2020 prediction for this solar cycle (as indicated by the red curve). Sunspot activity has consistently exceeded that 2020 prediction, sometimes considerably.

The continuing decline however suggests the April 2025 prediction is correct, that the ramp down to solar minimum has begun. The Sun could still surprise us and suddenly have a burst of new activity, but it increasingly looks like the maximum as truly passed, and we are heading for minimum.

If so, this cycle will be unusual, in that it will be both weak, and short. Since scientists began tracking the sunspot cycle in the 1700s, short sunspot cycles were always associated with cycles with a lot of sunspots. In this case the short cycle comes with a weak cycle, though slightly stronger than predicted.

As always, it must be stated the importance of the solar cycle to us on Earth. It tracks the Sun’s very tiny variability in total irradiance, which might have an impact on the global climate. Furthermore, there is circumstantial evidence that active cycles are linked to a warmer climate, and quiet cycles to a colder climate. If we ever hope to predict where the Earth’s global climate is heading, we need to better understand the Sun.

And right now that understanding is quite limited.