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Solar activity forecast for the period December 05 - December 11, 2025

Activity level: moderate
X-ray background flux (1.0-8.0 A): in the range B9.8-C3.6
Radio flux (10.7 cm): a fluctuation in the range 148-246
Events: class C (2-13/day), class M (0-4/period), class X (0-1/period), proton (0-1/period)
Relative sunspot number (Ri): in the range 78-156 

Vlastislav Feik
RWC Prague, Astronomical Institute, Solar Dept., Ondrejov, Czech Republic 

Geomagnetic activity forecast for the period December 05 - December 11, 2025

Quiet: Dec 8 - 9
Unsettled: Nov 5 - 7
Active: Dec 5 - 6, 10
Minor storm:   Dec 11
Major storm:  possible about Dec 11
Severe storm: 0

Currently, we record a partial geomagnetic activity decrease from storming level to unsettled to active one.
Unsettled to active conditions are expected within two coming days.
Geomagnetic activity minimum has been expected about Monday, December 8, and Tuesday, December 9.
At the end of currently forecasted period, we expect a geomagnetic activity enhancement again including a possible minor to major storm.

Tomas Bayer
RWC Prague
Institute of Geophysics of the ASCR, Prague
Department of Geomagnetism
Budkov observatory (BDV)

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere December 05 - December 11, 2025

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, December 4, 2025

The significant increase in solar activity since the beginning of December has finally confirmed the original assumption that the current 25th eleven-year solar cycle will have two peaks. The first occurred last October, while we have been eagerly awaiting the second one this year (especially in the fall). The increase in activity at the end of this summer started promisingly, but it was only the first of several. It was not until the large solar flare on November 11, 2025, which was the largest since October 3, 2024, that we knew the secondary maximum was near.

High solar activity period can be expected during the first half of December, while it is a bit of a shame that it did not occur a week or two earlier. This would have been particularly appreciated by shortwave radio amateurs, as the telegraph part of the largest competition – the CW WW DX Contest – traditionally takes place during the last weekend of November.

Although the current parameters of high-speed solar wind do not create exactly the structure of the Earth's ionosphere that we would like, at least the highest usable frequencies allow connections to be established on all shortwave bands. During December, we are likely to experience another increase in solar activity in the last third of the month, preceded by several days of increased geomagnetic activity.

F. K. Janda, A.R.S. OK1HH
http://ok1hh.nagano.cz/
Emails: ok1hh(at)crk.cz, ok1hh(at)rsys.cz
Pmail: OK1HH(at)OK0NAG.#BOH.CZE.EU

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