Solar Cycle 25: What to Expect on the Descent
Solar Cycle 25 peaked in late 2024, one of the strongest cycles in decades. Here's what the descending phase means for HF propagation and how to get the most out of the bands now.
Solar Cycle 25 peaked in October 2024 with a smoothed sunspot number well above predictions, making it the most active cycle since Cycle 22 in the early 1990s. We’re now roughly 18 months into the descending phase—and conditions are still excellent for anyone who’s been waiting for the right time to work HF.
Where We Are Now
The solar flux index (SFI) has been running in the 140–175 range through early 2026, down from the 220+ peaks of late 2024 but still far above the cycle minimum. For comparison, the floor of Cycle 24’s minimum ran SFI values in the low 70s. We have years of useful conditions ahead.
The F2 layer that supports long-distance HF propagation is still dense enough to support reliable 10m and 12m openings on most days of the week. That won’t last forever—conditions will continue declining toward the next minimum around 2030–2031—so the window for working rare DXCC entities on the upper bands is still open.
The Upper Bands: Use Them Now
10 meters (28 MHz) has been the story of this cycle. During the peak, 10m was open for transcontinental contacts for hours at a time—sometimes around the clock. Even now on the descent, 10m opens reliably to Europe and South America on most days from the Pacific Northwest. Check the band before you assume it’s closed.
12 meters (24.9 MHz) is perhaps the most underutilized band in amateur radio. It shares much of 10m’s propagation characteristics but sees far less traffic, which means shorter pileups and easier contacts. Worth programming into your scanning routine.
15 meters (21 MHz) remains the workhorse band for DX. It’s open longer than 10m and provides excellent paths to Africa, Asia, and the South Pacific throughout the day. If you can only work one band for DX, this is it right now.
The Middle Bands: Reliable and Underrated
17 meters (18.1 MHz) is a WARC band, meaning no contests—which also means a much quieter band. It’s open when 15m is open, often with better signal levels. Great for casual DX contacts and rag chewing.
20 meters (14 MHz) never really closes. It’s the most reliable band on the dial and will be the last to suffer as the cycle descends. The tradeoff is traffic—it’s the most crowded HF band. Expect pileups and QRM, but also expect it to be open when nothing else is.
What the Descent Looks Like
The descending phase of a solar cycle is not a cliff—it’s a slope. Each month, average SFI drops slightly. The upper bands become less reliable, the daily openings get shorter, and eventually 10m stops opening except near the equinoxes.
The pattern from previous cycles suggests:
- 2026: 10m and 12m still reliably open most days
- 2027–2028: 10m openings become more seasonal (equinox peaks, quiet summers)
- 2029–2031: Return toward minimum; 10m closes except for sporadic E and aurora openings; 15m becomes the new workhorse
This doesn’t mean the hobby gets less interesting—it just shifts. Low-band (80m and 40m) operators will see improving nighttime conditions as F2 ionization decreases. Digital modes like FT8 can exploit marginal paths that voice can’t. And we’ll get a Sporadic E season every summer regardless of the solar cycle.
Practical Suggestions
Work what’s open when it’s open. The upper bands are still excellent. Don’t wait for 15m to open on a day when 10m is long.
Log and track your worked entities. Use this window to chase DXCC entities that are hard to work at solar minimum. Africa, Oceania, and Central Asia are all reachable on 10m now in ways they won’t be in three years.
Keep an eye on propagation forecasts. The NOAA Space Weather Prediction Center publishes daily solar flux values and geomagnetic activity forecasts. A K-index above 4 can knock out propagation on the upper bands temporarily—worth checking before a contest weekend.
Explore 160m and 80m now. If you’ve been meaning to get into low-band DXing, the next several years of decreasing solar activity will progressively improve low-band conditions. Get your antenna up before the window is fully open.
The cycle will descend, but we’re not there yet. Cycle 25 is giving operators who show up a remarkable run of conditions. Make the most of it.