Weekly forecast

Solar activity forecast for the period June 27 - July 03, 2025

Activity level: low to moderate
X-ray background flux (1.0-8.0 A): in the range B4.5-C4.0
Radio flux (10.7 cm): a fluctuation in the range 80-165
Events: class C (1-12/day), class M (0-3/period), class X (0-0/period), proton (0-0/period)
Relative sunspot number (Ri): in the range 32-164	

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

Geomagnetic activity forecast for the period June 27 - July 03, 2025

Quiet: Jun 29 - 30
Unsettled: Jun 28, 31, Jul 3
Active: Jun 27 - 28, 31, Jul 1 - 2
Minor storm:  Jun 27, Jul 1 - 2
Major storm:  unlikely about Jul 1
Severe storm: 0

Because of persisting influence of the equatorial coronal hole, we expect active conditions also during the coming two days.
Since Saturday, June 28, we expect geomagnetic activity decrease to the unsettled level.
Last two days of June, we expect partial decrease to quiet to unsettled level before the other active event expected by the first three days of July.

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 June 27 - July 03, 2025

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere – June 26, 2025

The last significant solar flare was recorded on June 15, reaching an X-ray brightness of M8.4, while ejecting a CME into space. The particle cloud arrived at Earth on June 18, with the subsequent increase in solar wind speed, which caused an improvement in propagation conditions in the lower shortwave bands. Although eruptions with higher X-ray brightness were also recorded, they only caused shorter attenuation in the lower layers of the ionosphere on the illuminated part of the Earth.

Overall solar activity declined steadily after June 15, with five to six visible sunspot groups. While at most two were capable of producing larger eruptions. Their proximity to two of the three observable coronal holes near the equator made it possible to predict an intensification of the solar wind and the occurrence of geomagnetic disturbances for June 25-26 (or possibly also June 27). This was all the more likely given that it was the central meridian region. Since then, however, the sunspot groups and coronal holes have shrunk. The increase in solar wind speed (up to 700 km/s) and geomagnetic activity (only G1) was therefore smaller. However, the flux of electrons with energies above 2 MeV reached high values, with a maximum flux of 1,260 pfu at 25/1355 UTC.

Unfortunately, an increase in the concentration of free electrons in the Earth's ionosphere is a relatively common phenomenon this year and worsens the conditions for shortwave propagation. A return to background levels is expected from June 28. In July, larger sunspot groups will return to the solar disk. Therefore the solar flux will rise slightly during the first ten days. Only a very slight improvement in shortwave propagation conditions can be expected in the summer ionosphere of the Earth's northern hemisphere.

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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