By Courtesy of the Propagation team
G3YLA JIM
G0KYA STEVE
G4BAO JOHN
Its all about the weather
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Jim Bacon G3YLA
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and Nick Henwood
RSGB President.
Propogation News
10th July 2026
HF
3
We have had another week of mixed HF propagation. We started with a Kp index of 6.33 on Saturday July 4th, which was caused by a coronal mass ejection. This caused a strong (G3) geomagnetic storm and auroral conditions. A check on the bands on the fourth showed poor HF propagation with lower MUFs and weak and watery signals from the NCDXF beacons on 14.100MHz.
But conditions have since improved and we have had a Kp index of less than three over the past few days as this was being written, which means the ionosphere has returned to normal.
Meanwhile, the solar flux index has declined from a high of 203 on July 2nd to a low of 116 on July 8th. That’s quite a change and means that HF propagation has declined somewhat.
An Earth-facing coronal hole has now passed with few effects and currently there is nothing of significance rotating into view. Solar flare activity has also declined with only two M-class flares over the past three days.
So the big question is, what happens next? Active region 4482 on the Sun continues to be a major threat, as a solar flare and accompanying CME could soon ruin our chances of good HF conditions. The declining solar flux index hasn’t helped either.
With the WRTC about to start in East Anglia, NOAA puts the chance of an R1-R2 class solar event at 40% and an S1 solar radiation storm event at around one per cent. The greatest expected three-hourly Kp index for July 9-11 2026 is 3.67.
Again, NOAA predicts the SFI will be in the range 120-145 over the next week with a Kp index of two to three. So all good news overall.
DX to be worked this week includes D73G (Ch’ongsan Island), from July 17-19th, T22TT (Tuvalu), until July 16th, TY5FR (Benin), RT9K (Arctic Legends IOTA DXpedition), JK1HFB/JD1 (Ogasawara), until July 18th, OX3LX (Greenland) until July 17th and VP5G (Turks and Caicos), until July 30th.
May we take this opportunity to wish good luck to the 50 teams taking part in WRTC and good DX!
VHF and up
The weather is becoming a talking point in terms of the heatwave developing over much of the country, but especially in the south.
This has propagation implications too. It’s all being driven by a large area of high pressure, which for much of the coming week resides to the north and west of the British Isles. This will give a northeasterly breeze over the southeastern half of the UK which means it will be blowing in from the North Sea, possibly with areas of low cloud at times.
The propagation implication is that this represents almost ideal Tropo potential, especially when the low cloud moves inland, and we find a marked contrast between the hot dry air above the inversion and the cool, moist and shallow cloud layer below. However, in high summer the daytime heating over the land degrades the lift during the morning as the temperature inversion gets broken down by the strong sunshine.
Northern areas will see the occasional weakening front clip the northwestern fringes of the UK to offer up the only rain scatter prospects available at first, but some models are starting to suggest a breakdown by the end of the week, so more rain scatter and an end to the Tropo.
The prospects for aurora depend upon the Kp index, which at the moment is mostly cycling between Kp=1 and Kp=3, so not anything to generate radio interest, for which Kp=7 is nearer the mark. Meteor showers are still in the random state with the next shower, the Delta Aquarids, coming late in the month.
The Sporadic-E season is doing well this year and particularly given the activity levels on digital modes, but there have been events for CW and SSB up to 2m at times, but as typical for the mode, not all parts of the country experience an opening, so watch the clusters for early notice of workable paths.
EME now and declination reaches maximum on Sunday so Moon window lengths will peak along with maximum Moon elevation. Path losses are still falling, until perigee on the 13th of July. 144 MHz sky noise is moderate until Tuesday 11th when the Sun and Moon are close in the sky, then low for the rest of the week.
G3YLA JIM
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G0KYA STEVE
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