Propagation & Band Conditions
Current solar and propagation conditions affect HF radio communications. Use these tools to check band conditions before getting on the air.
Understanding the Numbers
SFI (Solar Flux Index)
Higher is better for HF. Values above 100 mean good conditions; above 150 is excellent.
SN (Sunspot Number)
More sunspots generally mean better HF propagation, especially on higher bands (10m, 12m, 15m).
A-Index
Measures geomagnetic activity. Lower is better — values under 10 indicate stable conditions.
K-Index
Real-time geomagnetic disturbance. 0-1 is quiet; 5+ means a geomagnetic storm (bad for HF).
More Resources
- SpaceWeather.com — Detailed space weather reports
- NOAA Space Weather Prediction Center — Official US space weather data
- DXMaps.com — Real-time propagation maps