Solar Cycle 25 beat its own forecast, and the bands are still open
2026-04-28 · EA5IYR
Every eleven years or so the Sun changes what shortwave is capable of. Solar Cycle 25 was forecast to be mild. It was not.
Sunspot numbers ran well above the original prediction, peaking at readings above 299 — figures not seen in decades — and elevated activity has continued through 2026. What sunspots have to do with your receiver
Shortwave travels far by refracting off the ionosphere, and the ionosphere is made by the Sun. More solar ultraviolet means more ionisation, which means the upper layers can bend higher frequencies back to Earth instead of letting them escape into space.
At a strong maximum: 10–15 MHz stays usable far later into the night than it has any right to. Above 15 MHz opens on daylight paths, often halfway around the world. 28 MHz and up comes alive — bands that sit nearly dead at solar minimum. Below 7 MHz gets worse: more daytime absorption, more noise.
That last point catches people out. A solar maximum is not uniformly good. It raises the ceiling and also raises the floor. What it means for what we track
Everything gets louder and travels further. Broadcasters can use higher frequencies and reach listeners who were out of range at minimum. Numbers stations that were regional become audible across continents. Over-the-horizon radars climb the spectrum too — logs of Container at 20 MHz are a solar-maximum phenomenon.
If you have ever wanted to hear the strange end of shortwave, this is the part of the cycle to do it in. Signals that need a decent path are getting one. The other side of an active Sun
The same activity that opens the bands also closes them.
A strong solar flare floods the lowest ionospheric layer with ionisation, and instead of refracting HF it absorbs it. The daylight side of the planet can lose the shortwave spectrum outright for anything from minutes to hours — a sudden ionospheric disturbance. There is nothing to do but wait.
Geomagnetic storms are messier still: paths over the poles degrade badly, sometimes for days, while the aurora becomes visible at latitudes that never normally see it. Using this practically
The propagation panel in FreqBuddy shows current band-by-band conditions, and the station map draws the grey line as it moves. Two rules of thumb carry most of the value: If a station will not come in, check whether the path is in daylight or darkness before assuming anything is broken. Around dawn and dusk at either end, try again. Absorption drops along the terminator and paths open that are impossible at any other hour.
Cycle 25 will decline from here. The high bands will close, and 28 MHz will go quiet again for years. It is worth listening while it lasts.
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Sources: ARRL, NOAA Space Weather Prediction Center, Radio World.