[SFDX] ARLP042 The ARRL Solar Report for October 16, 2026
Bill
bmarx at bellsouth.net
Fri Oct 16 13:02:28 EDT 2026
ARLP042 The ARRL Solar Report for October 16, 2026
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SB PROP @ ARL $ARLP042
ARLP042 Propagation Forecast
ZCZC AP42
QST de W1AW
Propagation Forecast Bulletin 42 ARLP042
From ARRL Headquarters
Newington, CT October 16, 2026
To all radio amateurs
SB PROP ARL ARLP042
ARLP042 The ARRL Solar Report
Look for improved propagation on the upper HF bands, as both the sunspot
numbers and 10.7-centimeter radio flux remain near or above 100.
According to NOAA's Space Weather Prediction Center (SWPC), the increase
in activity is being fueled primarily by sunspot Region 4551, which is
described as the largest and most complex of six sunspot regions
currently visible on the surface of the Sun. Mostly quiet geomagnetic
conditions are expected as well, with some disturbances possible late
next week.
The Australian Space Weather Forecasting Centre predicts mostly normal
HF propagation conditions worldwide.
The W3LPL Propagation Forecast from the Daily DX is predicting
significantly improved DX conditions on 10 and 12 meters for as many as
the next 10 days, with excellent conditions on 17, 15, and 20 meters as
well. DX openings on 30 meters should begin in late afternoon each day,
followed by 40 meters around an hour before sunset, and 80 meters just
after sunset.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, October 15, 2026, by F. K. Janda, OK1HH:
The so-called 27-day recurrence derived from the duration of one
rotation of the Sun around its own axis is often a useful tool for
forecasting fluctuations in solar activity. Although rare, there are
instances when the trend is exactly the opposite, which can be directly
misleading for predicting future developments. The most recent peak
solar flux of 136 s.f.u. on October 13 was measured exactly 27 days
after September 17, when the flux was 97 s.f.u. the first day of a
relatively long interval with low values below 100 s.f.u. Consequently,
the state of the Earth's ionosphere and thus shortwave propagation
conditions was not as favorable as might be expected at this time of year.
Furthermore, solar activity will decline for the remainder of October.
Although a disturbance in the Earth's geomagnetic field can be expected
after October 20, it should be brief, and the rest of the month is
expected to bring relatively calm and favorable conditions.
The Predicted Planetary A Index for October 16 to October 22 is 5, 5, 5,
5, 5, 15, and 20 with a mean of 8.6. The Predicted Planetary K Index is
2, 2, 2, 2, 2, 3, and 4 with a mean of 2.4. 10.7 centimeter flux is 100,
95, 95, 100, 100, 105, and 100 with a mean of 99.3.
For more information concerning shortwave radio propagation, see
*www.arrl.org/propagation*
<https://us.list-manage.com/Yzlf2CemWfu?e=f93f3f7181&c2id=a21bfabb4f8762c738ec6a6d5e4b235b&m=tyHXbGeq8ZHVSzRJ1zxVfnPXw59tnlkCUIWHEApqt0h1r6UNDAxOVBu5E3UE>and
the ARRL Technical Information Service web page at
*www.arrl.org/propagation-of-rf-signals*
<https://us.list-manage.com/1BupIUTXuLw?e=f93f3f7181&c2id=a21bfabb4f8762c738ec6a6d5e4b235b&m=SWiClImKNuPaO-A066LjZzjwFVEW-Jx82WSiyq2p9oqR7WqVEnlxpbIFUOxh>.
For an explanation of numbers used in this bulletin, see
*www.arrl.org/the-sun-the-earth-the-ionosphere*
<https://us.list-manage.com/x4Nj6zAeAUK?e=f93f3f7181&c2id=a21bfabb4f8762c738ec6a6d5e4b235b&m=VGGpO5ElJySH7vm-eHwujeqjfS9yU99sWmZcGAXrIXoYsdtv-6ksDJLeIT6E>.
Information and tutorials on propagation can be found at http://k9la.us.
NNNN
/EX
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