Weekly forecast

Solar activity forecast for the period December 19 - December 25, 2025

Activity level: low to moderate
X-ray background flux (1.0-8.0 A): in the range B4.0-C1.5
Radio flux (10.7 cm): a fluctuation in the range 104-168
Events: class C (2-10/day), class M (0-2/period), class X (0-1/period), proton (0-1/period)
Relative sunspot number (Ri): in the range 43-136

Karolina Knesplova
RWC Prague, Astronomical Institute, Solar Dept., Ondrejov, Czech Republic 

Geomagnetic activity forecast for the period December 19 - December 25, 2025

Quiet: Dec 20 - 21
Unsettled: Dec 19, 22 - 24
Active: Dec 22 - 25
Minor storm:   Dec 23 - 25
Major storm:  possible about Dec 25
Severe storm: 0

Beacuse of the coronal hole 09/+4, we expect a significant geomagnetic activity increase since Monday, December 22. 
Since this day, we expect active level return with possible minor storming events.
Possible but unlikely, a major storm event can be expected at the end of currently forecasted period. 

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 19 - December 25, 2025

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, December 18, 2025

The occurrence of an extensive coronal hole in the western half of the solar disk is consistent with the increased speed of the solar wind, as measured by geostationary satellites. The edges of another relatively large coronal hole in the east are likely to be the source of the next period of enhanced solar wind during the coming week. However, overall solar activity is low, as reflected in the low values of the critical frequencies of the F2 ionospheric layer.

The decline in geomagnetic activity in mid-December did, however, have a positive effect on shortwave propagation conditions, albeit mainly at lower frequencies. This included the occasional formation of ionospheric waveguides.

Although solar activity is likely to increase next week, the activity of the Earth's magnetic field is also likely to increase. Therefore, unstable conditions can be expected in the Earth's ionosphere, with short intervals of improvement followed by longer intervals of deterioration in shortwave propagation conditions.

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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