Solar & Space Weather
The space-weather inputs an HF propagation prediction depends on, in one place instead of four. Observations from NOAA’s Space Weather Prediction Center.
Propagation inputs
Planetary K index — last 3 days
Show as a table
| Time (UTC) | Kp | Condition |
|---|
Also right now
What this means for HF
Solar flux and sunspot number track ionisation of the F layer, which sets the maximum usable frequency. Higher values open the upper bands; when flux is low the MUF drops and the lower bands carry more of the traffic.
The A and K indices describe geomagnetic disturbance rather than ionisation. A disturbed field raises absorption and degrades paths that cross high latitudes well before it affects paths nearer the equator, so a quiet band on one circuit can be unusable on another.
These are observations, not a prediction. To turn them into a circuit-specific answer, put the flux or sunspot number into a point-to-point run.