HF Propagation Forecast & Solar Data
Updated
G7RDX is an amateur radio station in the north west of England, building live tools and writing build notes at the operating position.
Monitor real-time solar conditions and HF propagation forecasts. Check solar flux, K-index, sunspot numbers and band conditions to plan your next QSO.
Propagation Score
What the bands are doing right now, which one to use, and where to point the beam, scored for your grid square from live solar and geomagnetic data.
Propagation scorerefreshes every 10 minutes
— / 100
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Fetching live space weather from NOAA…
One number for how the bands are behaving right now, and what to do about it.
Band by bandscored for your grid
Estimated MUF — · bands above the MUF are unlikely to support F2 DX
Last 24 hoursscore history, kept in this browser
Solar conditionslive from NOAA SWPC
Geomagnetic conditionsa disturbed field closes polar paths first
Best time to operate todayAll times UTC
How is this score calculated?
| Component | Reading | Score | Weight |
|---|
Six components, each scored 0–100 and combined with fixed weights. Where a source is unavailable its weight is redistributed across the rest, so the score stays on the same scale rather than being quietly dragged down. It is a model of likely conditions, not a guarantee: the bands always get the final say.
Data sources
What it does
Turns the live solar and geomagnetic numbers into a single 0 to 100 score, then scores each band from 160 to 10 metres for your grid square, with the best band, a beam heading and the grey line windows.
Data and refresh
Solar flux, sunspot number, K and A indices, solar wind and alerts come from NOAA SWPC and refresh every 10 minutes. Sunrise, sunset and headings are computed from your Maidenhead locator in the browser.
How to read it
Above 70 the high bands are worth a listen; below 40 stay on 40 and 80 metres. A rising K-index closes the polar paths first. The 24-hour line shows whether things are improving or fading.
Who it is for
Operators who want to know which band to try before switching the radio on, and anyone learning what the solar numbers on the club noticeboard actually mean.
Frequently asked questions
What is a good propagation score for DX?
Anything above 75 means the bands should be in good shape and even SSB will get out. Between 55 and 75 is workable with CW or FT8.
What is a good solar flux index for 10m?
10m generally needs a solar flux index above about 150 for reliable worldwide F2 openings, and above 200 the band can stay open for most of the daylight hours. Below 100 the band is usually limited to sporadic E in season and short skip.
Does a high K-index kill HF propagation?
A K-index above 5 indicates a geomagnetic storm and will badly degrade HF, especially on paths crossing the auroral zone and the poles. The high bands lose their maximum usable frequency first, while the low bands suffer raised noise.
What is the grey line and why does it matter?
The grey line is the twilight band between day and night that sweeps around the Earth. For roughly an hour either side of your sunrise and sunset the D layer, which absorbs low band signals during the day, decays faster than the F layer.
How often is the propagation data updated?
Solar and geomagnetic figures come directly from the NOAA Space Weather Prediction Center and refresh every ten minutes on this page. The planetary K-index itself is published every three hours, while solar wind and X-ray readings update every few minutes.
What is the MUF and why does it matter more than the flux?
The maximum usable frequency is the highest frequency the ionosphere will still bend back to Earth on a given path at a given moment. Above it, your signal goes through the ionosphere and into space.
Why is 10 metres closed when the flux looks high?
Solar flux sets the ceiling, not the floor. Ten metres also needs the path to be in daylight, the geomagnetic field to be reasonably quiet, and the season to help.
Should I trust this score over my own ears?
No. The score is a prediction built from global measurements and your grid square, and it cannot know about your local noise floor, your antenna, or a sporadic E opening that started two minutes ago.