Weekly forecast

Solar activity forecast for the period July 25 - July 31, 2025

Activity level: low to moderate
X-ray background flux (1.0-8.0 A): in the range B4.3-C5.5
Radio flux (10.7 cm): a fluctuation in the range 92-183
Events: class C (1-13/day), class M (0-3/period), class X (0-0/period), proton (0-0/period)
Relative sunspot number (Ri): in the range 78-162	

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

Geomagnetic activity forecast for the period July 25 - July 31, 2025

Quiet: Jul 27 - 30
Unsettled: Jul 25- 27, 30 - 31
Active: Jul 25, 30
Minor storm: unlikely Jul 31
Major storm:  0
Severe storm: 0

Till now, at the Budkov observatory, the local K-index did not exceed the level 4.

We expect unsettled to active conditions persistence next day (Friday, July 25). The following days, we expect geomagnetic activity decrease to quiet  to unsettled level.
Geomagnetic activity enhance and an active episode return is possible at the end of currently forecasted period, about Thursday, July 31. Nevertheless, it can occur more likely during the next 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 July 25 - July 31, 2025

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere – July 24, 2025

Less than a year has passed since the probable peak of the 25th eleven-year cycle, which means that we are still in a period of high solar activity. This does not necessarily mean that there must be a high sunspot number, many eruptions, or a high level of solar radio noise power flux (or solar flux for short). Currently, here is mainly the high speed of the solar wind that alternately causes high concentrations of negatively charged free electrons in the ionosphere, which quickly recombine with positively charged protons. The result is irregular changes in shortwave propagation conditions, accentuated in the summer by the activity of the sporadic E layer.

From mid-July, sunspot activity initially increased, then declined significantly in the last third of the month as a result of the setting of larger sunspot groups. No major eruptions were observed in the setting groups. Therefore the Earth's magnetic field calmed down, especially on July 20-21. The geomagnetic disturbance on July 23 was expected, as the Earth entered the co-rotating interaction region (CIR), where it was hit by solar wind and triggered a G1-class geomagnetic storm (CIRs are transition zones between fast and slow solar wind streams and contain shock waves and amplified magnetic fields similar to those in CMEs).  

Forecasts of further developments from various sources now differ considerably. If we look at the part of the far side of the Sun that is currently hidden behind the eastern limb of the solar disk, we can first expect the current level of solar activity and, at the beginning of August, a slight decrease, accompanied by a slight increase in 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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