HF radio and space weather FAQ
Simple answers to the questions we hear most from amateur-radio operators and curious newcomers.
- Does a high SFI guarantee good HF conditions?
- No. SFI describes solar activity broadly. Kp, X-ray activity, local time, path geometry, antennas and noise can all change the result.
- What does a 70% reliability result mean?
- It is a model estimate for the selected path, frequency, time and mode. It is useful for comparing options, but it is not a promise of a successful contact.
- Why do live reports and the prediction disagree?
- Reports sample a limited set of stations and times. They may use different antennas, power and modes, while the model describes a wider path. Treat both as evidence.
- Which band should I try first?
- Start with the recommended frequencies in a path prediction. As a rule of thumb, lower bands often work better at night and higher bands often benefit from daylight and higher solar activity.
- Are the maps real-time?
- Each dataset has its own update interval. Check the timestamp shown beside a chart or map and the data-sources page before relying on it.