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Solar Cycle 25

SFI Kp Conditions

Updated 03:00 UTC 2026-04-07 · NOAA SWPC

Solar Cycle 25 began in December 2019. It is tracking above initial predictions and is relevant to every propagation measurement in this dataset — the higher the sunspot number, the more favorable conditions on the upper HF bands.

This page tracks cycle position using monthly SSN and SFI averaged from solar.bronze (GFZ Potsdam / SIDC data, backfilled to 2000).

Solar Cycle 25 began in December 2019 and is tracking well above NOAA's initial prediction of SSN 137. The current phase of high solar activity benefits upper HF bands (10m–17m) by raising the Maximum Usable Frequency.