On Friday, June 20, Spaceweather.com reports that, in addition to it
being the first day of Summer in the Northern Hemisphere, on June 19
the Sun produced another X-class flare causing a shortwave radio
blackout over the Pacific Ocean.

Solar activity reached high levels when Region AR4114 produced the
strongest event of the period, an X1.9 flare at 2350 UTC. The region
remained the most complex on the disk despite being in a decay
phase. The other numbered spotted regions on the visible disk were
either mostly stable or in gradual decay. No Earth-directed CMEs
were observed in available coronagraph imagery.

R1 to R2 (Minor-Moderate) radio blackouts are likely with a chance
for X-class flares (R3-Strong) through June 21, mostly driven by the
potential from Regions AR4114, AR4115, and AR4117.

Coronal Hole High Speed Stream conditions are expected to persist
with waning influences into June 21.  Unsettled conditions are
expected to continue.

Solar wind parameters continued to reflect a positive polarity CH
HSS (Coronal Hole High Speed Stream) regime.

The geomagnetic field is expected to be at quiet to unsettled levels
on June 21, and at quiet levels on June 22.  Geomagnetic field
activity is likely to reach G1 (Minor) storm levels on June 25 and
26 due to negative polarity CH HSS influences.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, June 19, 2025, by F. K. Janda, OK1HH:

"Solar activity is still at the peak of its eleven-year cycle, even
though it reached its maximum last summer (with a monthly average of
R = 216 in August last year and a smoothed average of R12 = 160.8
for October last year). The change from last year is the shift of
sunspot activity from the southern to the northern half of the solar
disc. The appearance of new sunspot activity in the southeast in
recent days, close to the solar equator, came as a slight surprise.

"This Spring, especially in May and early June, we could not fail to
notice frequent periods of solar wind intensification and,
consequently, a number of geomagnetic disturbances, which caused the
critical frequencies of the ionospheric F layer to drop to values
corresponding to significantly lower solar activity. In recent days,
there has been only a slight improvement.

"Most forecasts for future solar activity predict a continuing
decline, but if we assume higher activity in the currently setting
sunspot groups, we can expect an increase after their appearance on
the north-eastern limb of the solar disc in July. Overall, calmer
conditions can be expected during the coming Summer, although
shortwave propagation conditions will continue to be slightly worse
than would correspond to the level of solar activity."

The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found
on YouTube at, https://www.youtube.com/watch?v=3RXJT7qLT0A .

For customizable propagation charts, visit the VOACAP Online for Ham
Radio website at, https://www.voacap.com/hf/ .

For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals. For
an explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere . Information and
tutorials on propagation can be found at, http://k9la.us/ .

Also, check this:

https://bit.ly/3Rc8Njt

"Understanding Solar Indices" from September 2002 QST.

The Predicted Planetary A Index for June 21 to 27 is 5, 5, 8, 12,
25, 20, and 15, with a mean of 12.9.  Predicted Planetary K Index is
2, 2,3, 4, 5, 5, and 4, with a mean of 3.6.  10.7 centimeter flux is
138, 135, 125, 125, 130, 125, and 125, with a mean of 129.