Solar Cycle 25 and HF: What the Sunspot Data Says Now

For the last few years HF operators have enjoyed some of the best conditions in a generation, with 10 and 12 meters open for long stretches and 6 meters waking up far from the usual season. That raises an obvious question: where are we now in Solar Cycle 25, and how fast will the good conditions fade? This guide answers it with real numbers. It uses the NOAA Space Weather Prediction Center (SWPC) pages and its published observed and predicted cycle data, as available on 27 October 2026, and translates them into practical advice for amateur radio. The short version: the maximum has passed, activity is declining, and the decline will be gradual enough that the higher HF bands will still produce good days for a while.

What the Solar Cycle Is and Why Hams Track It

The Sun’s activity rises and falls in a cycle of roughly 11 years. The NOAA SWPC Solar Cycle Progression page shows the observed and predicted cycle in two forms: the sunspot number, and the F10.7 cm radio flux. Both numbers matter to radio amateurs. Sunspot number is a count of spots and groups on the solar disc. F10.7 is the radio noise from the Sun measured at a wavelength of 10.7 cm, in solar flux units, and it is closely related to the ionization of the upper atmosphere that supports HF propagation. Higher flux generally means a more strongly ionized F layer and better support for the higher HF frequencies. Our guide to solar flux, A-index and K-index explains how to read the daily numbers.

The cycle matters for planning, not just for curiosity. If you know that conditions will decline over the next years, you can decide when to chase DXCC entities on 10 and 12 meters, when to invest in low-band antennas, and what to expect from contests. The SWPC page itself says that the prediction gives a rough idea of the frequency of space weather storms of all types, from radio blackouts to geomagnetic storms to radiation storms, and is used by industries to gauge the expected impact in the coming years.

The Cycle 25 Record So Far

SWPC publishes the observed cycle indices as a data file. The values below come from that file and show the yearly averages of the monthly mean sunspot number for the years around the peak. The 2026 value covers January to September only.

A few more details from the same file. The smoothed sunspot number was only 1.8 in December 2019, which marks the minimum between Cycles 24 and 25. The highest monthly mean sunspot number of the cycle so far was 216.0 in August 2024, and the highest smoothed value was 160.9 in October 2024. The highest monthly F10.7 was 245.6 in August 2024, and the highest smoothed F10.7 was 194.5 in October 2024. The latest complete month in the file is September 2026, with a monthly sunspot number of 60.3 and F10.7 of 105.41. These are real observed values, but remember that the smoothed numbers need several months of data after a given month, so the most recent months have no smoothed value yet.

How the Forecasts Compared

The SWPC page describes two predictions. The first came from a NOAA, NASA and ISES panel convened in 2019, which received nearly 50 distinct forecasts from the scientific community and synthesized them. It predicted a maximum of 115 in July 2025, with error bars of 105 to 125 and a peak between November 2024 and March 2026. The second is an updated prediction that SWPC describes as a re-calibration based on new observations; it was made available as an experimental product in October 2023 and replaced the panel prediction on the website in February 2025. The panel prediction can still be displayed from a drop-down menu.

The observed numbers show how much the cycle exceeded the 2019 forecast. The smoothed maximum in the data file was 160.9, far above 115, and it occurred in October 2024, within the window the panel allowed for the timing but not for the size. That is a useful lesson for anyone who relied on early forecasts: cycle predictions can be wrong by a large margin, especially in amplitude, and the right approach is to follow the observations and the monthly updates.

What the Current Forecast Says

The SWPC predicted cycle file, which begins in April 2026, gives a monthly value for the smoothed sunspot number and F10.7, together with bands of uncertainty. Sampling it each October gives a clear picture of the decline:

• October 2026: predicted smoothed sunspot number 87.9 and F10.7 125.9.
• October 2027: 65.9 and F10.7 103.8.
• October 2028: 38.7 and F10.7 85.1.
• October 2029: 20.2 and F10.7 75.3.
• October 2030: 9.3 and F10.7 70.8.

The SWPC page also notes that Solar Cycle 26 is expected to begin some time between January 2029 and December 2032, and that SWPC does not yet produce a prediction for it. The shaded regions on the page show uncertainty derived from earlier cycles: there is roughly a 25% chance that the smoothed sunspot number will fall within the darkest shaded region at a given time, a 50% chance for the medium region and a 75% chance for the lightest. In other words, the numbers above are central estimates and not promises.

What It Means for the HF Bands

Treat the following as rules of thumb, not guarantees. When the daily solar flux is high, the F2 layer supports higher frequencies, so 10, 12 and 15 meters open widely. As the flux falls toward 100 and below, the highest bands open less often and for shorter periods, and the center of activity shifts down to 20 and 17 meters. Around solar minimum, 20 meters still opens, while 15 and 10 meters can be nearly dead for days. The forecast above suggests a smooth slide: by late 2027 the predicted F10.7 is around 104, which is still capable of good 15 and 17 meter days, but by 2029 it is near 75, a value typical of quiet years.

• 10 and 12 meters: expect fewer and shorter openings each year. Our 10 meter band guide describes how to catch what remains.
• 15 and 17 meters: still the best daytime DX bands for several more years; see our 15 meter guide.
• 20 meters: the stable workhorse through the decline.
• 40, 80 and 160 meters: the low bands are often said to improve at solar minimum because daytime absorption falls, so keep your low-band antennas in good shape.
• 6 meters: sporadic-E openings do not follow the solar cycle in the same way, so summer openings will continue, but F2 openings on 6 meters will become rare.

Why Declining Does Not Mean Dead

A declining cycle still has strong days. Solar activity is noisy: a single large active region can lift flux for a week even when the monthly average is falling, which is why the data file shows a jump to 101.8 in May 2026 after 79.0 in April. Looking only at the trend line loses those opportunities. For planning, use the daily solar flux and a tool such as VOACAP, which takes the smoothed sunspot number as an input to predict which bands will be open on a given path and hour.

The decline also brings a different kind of risk: geomagnetic storms and flares continue throughout the declining phase of a cycle, and radio blackouts can still interrupt HF contacts. Our guide to HF propagation explains how the main drivers of HF conditions work.

Why Smoothed Numbers Lag Behind

When you look at cycle charts you will see two kinds of values: the monthly mean and the smoothed value. A smoothed value is an average that runs across many months around the date in question, so it cannot be computed for a month until the following months have been observed. That is why the latest months in the SWPC file carry a placeholder instead of a smoothed value, and why the peak of a cycle can only be named with confidence long after it has happened. The monthly values are noisier, but they are available at once and show real swings. In the file, for instance, the monthly sunspot number fell from 114.8 in October 2025 to 91.7 in November, then rose to 124.2 in December 2025, while the smoothed number moved slowly the whole time.

For daily operating decisions neither of these numbers is the right tool. The monthly and smoothed values describe the trend. The daily flux and the geomagnetic indices describe what is happening today, and the ionosphere responds to the day’s numbers within hours. A practical habit is to use the trend for your annual plan and the daily values for your weekend.

Planning Contests and DX Chasing During the Decline

A declining cycle changes the way experienced operators plan. Contests that were dominated by 10 meters in 2024 will increasingly be decided on 15 and 20 meters, and the multipliers on the highest bands become more valuable because fewer stations can work them. If you chase DXCC entities, the sensible approach is to use the remaining high-band openings on the countries that are hardest to hear on 20 meters, and leave the easy entities for later. Our guide to long path DX shows another way to find openings when the direct path is closed.

It is also a good moment to look at your station as a whole. High bands are forgiving, because a modest antenna and low power can still reach far when the F2 layer is strongly ionized. As activity falls, antenna gain and height count for more on every band. Improving the low-band antennas and receive systems pays off over a longer period than any single season of good conditions.

Finally, keep your expectations realistic about forecasts. The forecast values in this article are SWPC’s central estimates from its published file. The uncertainty shown on the page grows with time, and the actual numbers will differ. When the next month’s data arrive, the forecast moves, and this article’s figures will be out of date. That is the nature of the cycle, and part of the pleasure of following it.

How to Follow the Cycle Yourself

1. Visit the SWPC Solar Cycle Progression page once a month to see the new data points and how they compare with the prediction. The page says the prediction is updated every month as more observations become available.
2. Check the daily flux and A and K indices before an operating session or contest, since they tell you today’s conditions rather than the long-term trend.
3. Keep a short log of which bands opened to which regions. After a year you will have your own record that is more useful than any average.
4. Use the Wikipedia article on Solar Cycle 25 for the background story of how the cycle compared with earlier ones.

The Bottom Line

Solar Cycle 25 peaked in 2024, well above the 2019 panel forecast, and has been declining since. Yearly average sunspot numbers fell from 154.5 in 2024 to 123.5 in 2025 and 85.3 so far in 2026, and NOAA’s current forecast takes the smoothed sunspot number from about 88 this month to about 66 in October 2027 and below 10 by October 2030. Use the high bands while they last, keep an eye on daily flux, and prepare your low-band antennas for the years when the upper bands go quiet.

Frequently Asked Questions

Has Solar Cycle 25 peaked?

In the SWPC data the highest smoothed sunspot number was 160.9 in October 2024, and activity has declined since. Smoothed values for the most recent months are not available yet.

What is F10.7?

F10.7 is the radio flux from the Sun at a wavelength of 10.7 cm, measured in solar flux units, and it is a standard indicator for HF propagation conditions.

How good was the original forecast?

The 2019 panel predicted a maximum of 115 in July 2025. The observed smoothed maximum was 160.9 in October 2024, so the cycle was stronger and earlier than that forecast.

When will Cycle 26 start?

SWPC says Solar Cycle 26 is expected to begin some time between January 2029 and December 2032 and does not yet produce a prediction for it.

Will 10 meters still open in 2027?

Yes, on good days. The forecast F10.7 in October 2027 is about 104, so openings will be less frequent but not gone.

Where do I find the data?

On the NOAA SWPC Solar Cycle Progression page, which also links to the observed and predicted data files.