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Solar Cycle 25

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).


Cycle Position

Metric Value
Current Monthly SSN
12-Month Smoothed SSN
Cycle 25 Start December 2019
Estimated Peak
Months Since Cycle Start
Predicted Peak SSN (NOAA) 137
Actual Peak SSN (so far)

Coming soon — requires monthly SSN aggregation query.


Monthly SSN and SFI — Solar Cycle 25

Monthly averages from solar.bronze. Smoothed SSN uses a 13-month centered running mean.

Month Monthly SSN Smoothed SSN Monthly SFI Smoothed SFI

Coming soon — requires monthly solar aggregation query.


Cycle 24 vs Cycle 25 Comparison

Month-by-month comparison at the same point in each cycle. Cycle 24 peaked at SSN ~116 (April 2014). Cycle 25 comparison starts from December 2019.

Months Into Cycle Cycle 24 SSN Cycle 25 SSN Cycle 25 Ahead/Behind

Coming soon — requires cross-cycle comparison query.


IONIS Prediction Accuracy Over the Cycle

Pearson correlation between IONIS predictions and measured WSPR SNR, grouped by 6-month intervals. Higher solar activity generally improves prediction accuracy on upper bands.

Period Avg SSN IONIS Pearson RMSE (sigma) Sample Count

V20 production model trained on data through 2025. Correlation metrics computed on held-out test sets.