The Sun peaked in October 2024. In 18 months it lost 45% of its sunspots.

That is a steeper fall than almost every cycle on record. Here is the proof, then your chance to forecast what comes next.

01Now you forecast: what will the count be in April 2028?

The orange line is Cycle 25 so far (13-month smoothed sunspot number). Drag the slider to where you think it will be 42 months after the peak, then lock it in. Past cycles will then replay their decline from today's level.

02Every cycle since 1755, lined up at its minimum

Pick up to six cycles. Is Cycle 25 a giant like Cycle 19, or a dwarf like Cycle 24? Touch or hover the chart to read a month.

03Sources and method

• Monthly sunspot numbers, 1749 to October 2026 (3,334 months) and the Cycle 25 forecast: NOAA Space Weather Prediction Center, observed-solar-cycle-indices.json and predicted-solar-cycle.json, fetched 4 November 2026. The shaded forecast band is NOAA's published uncertainty (up to the 75th percentile of past forecast errors, see its Solar Cycle Progression page).
• Cycle start months: the List of solar cycles on Wikipedia secondary, which cites SILSO (Royal Observatory of Belgium). The smoothed peak values I compute below match its table (for example 285.0 for Cycle 19 and 160.9 for Cycle 25).
• Smoothing: the standard SIDC 13-month formula (months -5 to +5 weighted 1, months -6 and +6 weighted 0.5), described by SILSO. The newest 6 months cannot be smoothed yet, so the smoothed line ends in April 2026.
• Analogs in section 01 are my own calculation, not a forecast: each past cycle's smoothed curve after its peak is rescaled so that its value 18 months after the peak equals Cycle 25's April 2026 value. That keeps the shape of each decline and removes differences in size. Cycles with the same peak month are aligned on that month.

Built 4 November 2026. Sunspot numbers are revised by SILSO from time to time.