RSGB
GB2RS News Team | September 26, 2025
Last week was good for HF propagation for a number of reasons. Firstly, we are now entering autumn, which offers better propagation prospects than summer. Secondly, the solar flux index has remained high at up to
184 as of last Thursday, 25 September.
We had a week of near-normal geomagnetic conditions, with a low Kp index, no Earth-directed coronal mass ejections, and a relatively quiet solar wind.
These have all combined to give excellent HF propagation, including openings on the 10m band using FM and transatlantic 10m contacts being possible in the afternoon.
The maximum useable frequency, or MUF, over a 3,000km path, according to Propquest, has mainly been in excess of 30MHz during daylight hours.
The KQ2H repeater in upstate New York, with an output frequency of 29.620MHz, has been loud at times in the afternoon and is a good indicator of HF propagation. Expect it to get better as we enter October. Other US stations have also been heard on the 10m band using FM, including one in Ohio.
Steve, G0KYA was surprised to hear the GB3XMB 10m beacon on 28.287MHz from Waddington, Lancashire this week. Steve remarked that it is 175 miles to Norfolk as the crow flies. He said that the signal didn’t sound like backscatter, so that’s quite a distance for 10m ground wave.
Other DX worked, according to CDXC, included FP5KE, the St. Pierre and Miquelon DXpedition. The station could heard on everything from Top Band to 10m.
V6D in Micronesia has been working on the 40 and 17m bands using CW.
Other highlights include D2USU in Fiji on the 12m band using FT8, and 9Y49R in Trinidad and Tobago on the 10m band using FM.
Next week, NOAA predicts the solar flux index may fall to be in the 159 to 170 range. Geomagnetic conditions are predicted to be poor tomorrow,
29 September, with a Kp index of 5, and again between the 3 and 5 October, also with a predicted Kp index of 5. Expect decreased MUFs for a few days until the ionosphere recovers.
VHF and up:
The next week or so looks to be typical for autumn. It will be a mix of Atlantic weather systems bringing lows and their fronts which may offer some rain scatter for those on the GHz bands.
The other side of the coin is areas of high pressure or mostly weak ridges, in this case mainly affecting the south and east of the country.
This is the point where Tropo operators can move in with paths probably favouring the North Sea and Scandinavia up to this weekend and then across to the continent and down to Spain during the coming week.
It is worth remembering that Tropo can exist throughout the 24 hours across water and along coasts like the North Sea and English Channel, although the portion of a path overland can weaken during daytime.
The meteor scatter prospects remain in the random territory, so they are best in the early morning.
Recent activity with geomagnetic disturbances suggests that aurora should continue to be part of the operating list in the coming week.
Check for a hollow note or warble on HF signals and for a Kp index greater than 5, then consider turning your VHF arrays to the north.
For EME operators, Moon declination reaches its minimum tomorrow, 29 September, so from then on we will see lengthening Moon windows and increasing peak elevation. The Moon’s distance from Earth started to decrease after apogee on Friday, 26 September, meaning path losses are falling. 144MHz Sky noise will be high today, the 28 September, and peaks at around 2800 Kelvin tomorrow, 29 September, before dropping back to low for the rest of the week.
(Mike Terry, UK/BDXC)
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