RSGB
GB2RS News Team | August 22, 2025
Last week was relatively good from an HF propagation standpoint, with only a few periods with an elevated Kp index thanks to a high-speed solar wind stream from a coronal hole.
The Kp index hit 4.67 on the 19 August and 4 again on the 20 August due to the solar wind hitting earth at more than 600 kilometres per second.
Luckily, the interplanetary magnetic field remained mostly neutral, or north-facing, and the density was low, saving us from more disruption.
Meanwhile, the solar flux index declined to 120 by Thursday the 21 August. This is still high enough to affect the ionosphere, but well down on recent highs in the 140s and 150s.
The daytime critical frequency has mostly remained above 7.5MHz, meaning the 40m band has managed to remain good for inter-UK contacts. This has also meant that maximum usable frequencies, or MUFs, over a 3,000km path hit 21MHz and even 24.9MHz at times. Night time critical frequencies have been around 5MHz, giving an MUF over 3,000km of below 14MHz and sometimes even as low as 10MHz.
It may be another month or so before we see daytime F2-layer openings starting again on 28MHz. In the meantime, focus your efforts during daylight on 21MHz and below.
T30TTT in Western Kiribati remains one of the DX stations to chase, mostly on 18 and 21MHz. The operators are alternating between using CW, SSB and FT8. Other choice DX worked included Jim, E51JD on South Cook Islands who has been active on the 17m band using SSB. TY5AD in Benin, Africa has been worked on the 10m band using FT8. And 3G1P, an IOTA DXpedition in Chile, was logged on the 15m band using SSB.
Closer to home, today, the 24 August, is the last chance to work OG0C on the Aland Islands.
Next week, NOAA predicts that the solar flux index will remain in the 120s, until the end of the month when it could rise to 130 and even 150.
Unsettled geomagnetic conditions are forecast for the 28 August when the Kp index could hit 4.
Otherwise, make the most of the relatively settled conditions over the first half of next week to work some choice DX!
VHF and up:
After this weekend, the weather changes from a Tropo high pressure pattern to an unsettled story with areas of low pressure and fronts together with wind and rain. This will remove any Tropo options and replace them with a possibility of rain scatter on the GHz bands.
The auroral conditions have recently produced minor enhancements, although nothing too exciting so far radio-wise. It’s worth noting that the autumn, along with spring, are times of the year when auroras are more likely. So, it’s a good time of the year to keep abreast of the Kp index, especially if the Kp index goes above 5.
We are at the tail end of the broader period of the Perseid meteor shower, ending today, the 24 August. This leaves random meteor activity as the only option for a while. As those of you who are active in the mode already know, it tends to favour the early pre-dawn period for better chances of catching meteor scatter.
Sporadic-E is hanging on for the last week or two of the 2025 season, but opportunities become much rarer. You’ll need to keep a close watch on band reports to capture these increasingly fleeting events. In the main Sporadic-E season, there are usually two well-defined peaks of activity in the morning and late afternoon. However, in the tail of the Sporadic-E season you are just as likely to find it around the middle of the day as at any other time.
The daily Sporadic-E blogs at propquest.co.uk finish at the end of August, but in some years the last events have extended into the first week of September.
Moon declination is still positive, but falling, going negative on Monday. So, Moon window lengths and peak elevation will follow suit.
Path losses are rising again as we approach apogee on Friday 29 August.
144MHz sky noise was low until lunchtime on Friday 22 August, when the Sun and the Moon were very close in the sky. This continued throughout the Moon window on yesterday, the 23 August, and will revert to moderate-to-low next week.
(Mike Terry/BDXC)
