10M & 6M Are Still Open Solar Cycle 25 Update | Greyline
The Signal Lab — Propagation
10M & 6M Are Still Open Late Into the Night. What’s Changed?
Updated April 20, 2026 — originally published March 2023
April 2026 — Where We Are Now
Cycle 25 blew past every prediction. NOAA forecast a peak SSN of 115 — the actual smoothed sunspot number reached well above 200, nearly double. Maximum was confirmed in late 2024, but the Sun didn’t read the memo on when to stop. We are now on the descending slope — but “descending” doesn’t mean quiet.
Strong X-class flares, complex sunspot groups, and sporadic high-activity periods are still occurring regularly through early 2026. The high-band DX window — 10M, 12M, 15M, and the 6M magic band — remains open. This is still a historic operating period. Don’t put the radio away.
Cycle 25 Progression
The Numbers — Then and Now
NOAA / SWPC Solar Cycle 25 Progression — updated April 2026. The actual cycle (black line) significantly exceeded the original forecast (dashed). We are now on the descending slope.
Historical cycle shape for reference. Cycle 25 tracked higher and faster than this projection suggested at cycle start.
The Original Signal
Frank W3LPL Saw It Coming
In March 2023, Frank Donovan W3LPL — one of the most respected HF propagation observers in the country, operating from Maryland with a world-class station — wrote to his club’s email reflector about unusual 6-meter activity. We shared it then and it’s worth revisiting now with the benefit of what actually happened.
“Like many — but not all — above-the-MUF 6-meter propagation reports, the openings are often brief but much more frequent than in recent years because of increased MUFs as we rapidly approach Solar Cycle 25 solar maximum. As we approach Spring — especially from late April through most of May — enhanced F2 openings will become increasingly frequent and long-lasting.”
— Frank Donovan, W3LPL, Maryland (March 12, 2023)
He was right, and then some. What followed was one of the strongest high-band cycles in decades. K7GS in Washington State was logging the Middle East on FT8 at 2 AM local. S9+ European signals were appearing on 10M during the daytime. The Falkland Islands were workable from the mid-Atlantic. These weren’t anomalies — they became routine for operators paying attention.
The physics, plainly stated
What drives 6M F2 openings is enhanced ionization in the Equatorial Ionization Anomalies — ionospheric concentrations located roughly 700 to 1,400 miles north and south of the geomagnetic equator. When sunspot numbers are high, these anomalies become more ionized, pushing the Maximum Usable Frequency (MUF) above 50 MHz.
For most U.S. operators (north of the Gulf states), a direct path into the northern anomaly isn’t possible — you need either a sporadic-E patch at a strategic intermediate point, or a rare above-MUF enhancement at your latitude. During the Cycle 25 peak years, those conditions appeared far more often than in any recent cycle.
Reference: K6MIO’s classic paper “F-Region Propagation and the Equatorial Ionospheric Anomaly” covers the mechanics in full. [4]
DXMaps 50 MHz activity during a 6M opening in March 2023 — the kind of map that became common through 2024–2025. Watch dxmaps.com live during your next session. [2]
What the Descent Means for You
The Window Is Narrowing — But Not Closed
Cycle descents are not cliffs. Historical cycles show that strong high-band conditions persist well into the declining years — Cycle 23, which peaked in 2001, was producing exceptional 10M and 6M events through 2004 and 2005. The rate of decline matters more than whether you’re past peak.
What changes during descent is the predictability of openings. Near maximum, the bands were often open before you even sat down. Descending, you need to pay more attention to solar flux numbers, K-index, and propagation tools. The operators who stay active and watch conditions carefully will continue to work DX that occasional operators miss entirely.
Practical guidance for 2026
Watch solar flux (SFI) daily — above 150 means 10M and 12M are likely productive. Above 200, check 6M. Keep an eye on K-index: K=0–2 is good, K=3 is workable, K=4+ means skip the low bands and check 10M for short-path openings that survive moderate geomagnetic activity. Spring and summer (late April through July) remains the best seasonal window for 6M F2 from the U.S. — that has not changed. Get on the air. The bands won’t be this open again until approximately 2034.
A Resource Worth Bookmarking
CT1BOH — José Carlos Nunes, Portugal
José Carlos Nunes, CT1BOH, is a world-class contester and DXer operating from Portugal — sitting at the crossroads of European, African, and transatlantic propagation paths — who has assembled one of the cleaner live propagation dashboards on the web. His page pulls real-time NOAA SWPC data: K-index, geospace timeline, aurora forecasts, solar wind, and the 12-month ahead cycle prediction. It’s a working tool, not a static page.
His explanation of the space weather scale — R1 through R5 for radio blackouts, S1 through S5 for solar proton events, G1 through G5 for geomagnetic storms — is among the clearest summaries available without wading into NOAA’s technical documentation. If you want to understand why the bands went dead this morning, his page tells you in plain terms.
CT1BOH Propagation & Space Weather Dashboard
Live K-index, geospace timeline, aurora forecast, solar wind data, and sunspot cycle prediction. Updated in real time from NOAA SWPC and BOM Australia feeds.
Visit CT1BOH Propagation →Your Antenna & the Magic Band
Every Greyline Covers 6M
Every Greyline antenna — 12 through 28 feet — radiates on 6 meters. Most modern transceivers cover 50 MHz. If you have a Greyline up and an HF rig, you already have a 6M station. No separate antenna, no modifications. Tune up with your ATU and watch PSKreporter light up the map during the next opening.
The 5/8λ sweet spot for a 12-foot Greyline is 6M — it’s the one height where the shortest model has a natural gain advantage on the band most likely to open unexpectedly this spring. If you have the 12-footer and haven’t tried 6M yet, now is the time.
Resources & References
[1] NOAA SWPC — Solar Cycle 25 Progression (live)
[2] DXMaps — Live 50 MHz activity map
[3] Frontiers in Space Sciences — Solar Magnetic Activity deciphered
[4] K6MIO — F-Region Propagation & the Equatorial Ionospheric Anomaly (PDF)
[5] CT1BOH — José Carlos Nunes — Live Space Weather & Propagation Dashboard
[6] W3LPL — Frank Donovan, Maryland — original 6M cycle 25 analysis (club reflector, March 2023)
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Ham Radio is fun again. Pass it on… 73, Jon KL2A & the Greyline Performance Team