The STCE's SC25 Tracking page has been updated to reflect the latest evolution of some critical space weather parameters for the ongoing solar cycle 25 (SC25). It covers various aspects of space weather, from sunspot numbers over geomagnetic indices all the way to cosmic rays. The multiple graphs allow for a comparison with previous solar cycles at similar stages in their evolution.
The graph below shows the monthly and SILSO smoothed monthly sunspot number (SIDC/SILSO) from around the start of SC23 up to the current SC25. The prediction for the ongoing solar cycle 25, which started in December 2019, is displayed in green. Following the maximum of the smoothed monthly sunspot number in October 2024, the overall solar activity has been gradually declining. "Declining" does not mean "non-existing". Indeed: over the last 5 months, i.e. from from October 2025 till February 2026, 2 of the 10 strongest X-class flares so far this solar cycle were recorded, as well as one of the most flare-productive sunspot groups in decades. November 2025 saw the strongest Ground Level Enhancement so far SC25, while in January 2026 a severe proton event rich in low-energy protons was registered. And on top of that, November 2025 and January 2026 saw an -almost- extremely severe geomagnetic storm, with aurora spotted over Belgium in both cases. Over the next 2 years, further episodes with very enhanced solar and geomagnetic activity can be expected.
Many other parameters such as the sunspot area and the 10.7cm solar radio flux are following the sunspot number's declining trend. In contrast, some other parameters are exhibiting an overall increase. An example is the planetary A index ("Ap" - see the STCE SWx classification page), which reflects the level of disturbance of the geomagnetic field. Following severe geomagnetic storms in November 2025 and January 2026, this Ap index is now on the rise to a new high for this solar cycle. This can be seen in the graph underneath, with the current evolution in green, the average of the previous 8 solar cycles in orange, and the corresponding standard deviations reflected by the dashed lines.
