By Courtesy of the Propagation team
G3YLA JIM
G0KYA STEVE
G4BAO JOHN
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Jim Bacon G3YLA
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and Nick Henwood
RSGB President.
Propogation News
25th September 2026
HF
3
As we head towards the end of September, we are seeing daytime maximum usable frequencies starting to climb. The daytime MUF over 3,000km is reaching 12 metres and is just touching 10 metres at times.
Within a few weeks we can expect it to reach 10 metres on a regular basis, perhaps bringing transatlantic QSOs to 28MHz once again.
Meanwhile, we can make the most of the openings on 17, 15 and 12 metres, which are showing promise with increasing propagation to Asia, North Africa, South Africa and South America.
The solar flux index is hanging in there. Last week it fell to 96, but then rebounded back into the low 100s. There are currently eight sunspot groups visible on the Sun. The good news is that geomagnetic conditions have been calm, with the Kp index mostly in the ones and twos.
That could soon change, however, thanks to a large coronal hole on the Sun’s surface.
These are dark, cool, and less dense regions in the Sun’s outer atmosphere, when viewed in ultraviolet, with open magnetic field lines. This one stretches from the solar equator to its pole. At the time of writing it looks like we could end up with a Kp of five, perhaps on Thursday 24th or Friday 25th. There are also two coronal holes following it, which may cause more problems.
With the equinox, we often see more auroral activity, due to the Earth-Sun alignment and the Russell-McPherron effect.
Once auroral conditions clear, the Kp index should return to normal, with a Kp of two predicted from the 28th onward. The SFI may even improve slightly, with a forecasted solar flux index of 115 towards the end of the month.
Make the most of the HF conditions by working one of the DX stations on air. Choose from 5W0AF (Samoa), JD1BON and friends (Ogasawara Islands), OX3LX (Greenland), FR/F1TEQ and FH/F1TEQ (Reunion and Mayotte) and 8Q7JH (Maldives).
VHF and up
Recently, the overall characteristic of the weather in southern areas has been one of high pressure, giving some occasional Tropo. This region of high pressure will drift away by this weekend as a deep low over the northern Atlantic drives a weakening cold front south, so any major Tropo will probably not survive into next week. The rest of the period looks unsettled generally.
The northern half of Britain will have the more active part of any weather system crossing the country and therefore will also have the better chance of some rain scatter on the GHz bands.
This time of the year we often get some very active Atlantic storms and although they may not cross the UK directly, they may be close enough for severe gales and damaging winds in northwestern areas by the middle of next week, so make sure those antenna guys are in good shape and keep an eye on the forecasts.
There are no major meteor showers in the period, so once again any activity is likely to be random input and this is typically best in the hours just before dawn.
The prospect for auroras is a little more interesting since we are now just past the equinox of September 22nd. It’s a preferential time to be alert for auroras due to the way the Earth’s magnetic field aligns better with the Sun’s, and thus makes it easier for the solar wind to get through and create auroras. There was an interesting item about this Russell-McPherron effect on https://www.spaceweather.com last Tuesday, 22 Sep 26.
EME now, and Moon declination goes positive at Moonset on Friday the 25th so we’ll see lengthening Moon windows, and higher peak Moon elevation into the following week. Path losses continue to fall. 144 MHz sky noise starts the week low, increasing to moderate by Friday October 2nd.
G3YLA JIM
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G0KYA STEVE
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