[SFDX] ARLP036 The ARRL Solar Report

[Bill]

ARLP036 The ARRL Solar Report

	

SB PROP @ ARL $ARLP036

ARLP036 Propagation Forecast

ZCZC AP36

QST de W1AW

Propagation Forecast Bulletin 36 ARLP036

 From ARRL Headquarters

Newington, CT September 4, 2026

To all radio amateurs

SB PROP ARL ARLP036

ARLP036 The ARRL Solar Report

Forecast of Solar and Geomagnetic Activity, courtesy of NOAA Space 
Weather Prediction Center, 31 August - 26 September 2026.

Solar activity is expected to be at very low to low levels, with a 
chance for moderate levels and a slight chance for high levels 
throughout the forecast period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected 
to be at high levels on 31 Aug - 06 Sep, then again from 16-23 Sep. 
Levels are expected to be at normal to moderate levels from 07 - 15 Sep, 
and again from 24-26 Sep.

Geomagnetic field activity is expected to decrease from unsettled levels 
on 31 Aug to mostly quiet levels from 01-11 Sep and again from 17-23 
Sep. Unsettled to active conditions are expected from 12-16 Sep due to 
negtive polarity CH HSS influence, then again from 24-26 Sep under 
positive polarity CH HSS influence.

Weekly Commentary on the Sun, the agnetosphere, and the Earth's 
Ionosphere, September 3, 2026

A moderately strong solar flare (class M3.0), which peaked in the 
northeastern part of the solar disk on September 2 at 19:36 UTC, was 
accompanied by a coronal mass ejection (CME). This occurred in NOAA 
active region No. 4524, which was observed as NOAA No. 4510 during the 
previous solar rotation. Based on its reappearance and activity, we can 
conclude that the expected decline in overall solar activity in the 
first half of September will not be as severe as originally anticipated.

In the first half of September, we can expect only a very gradual 
increase in solar activity and likely only a few geomagnetically active 
days. Above all, however, we can expect a recurring rise in solar 
activity around the autumn equinox which is precisely the combination 
that typically leads to a noticeable improvement in ionospheric 
propagation of shortwave signals. The subsequent rise

in geomagnetic activity immediately following the equinox could, with a 
bit of luck, bring another brief, follow-up improvement at its onset.

The Predicted Planetary A Index for September 4 to September 10 is 5, 5, 
5, 5, 5, 5, and 5 with a mean of 5.0. The Predicted Planetary K Index is 
2, 2, 2, 2, 2, 2, and 2 with a mean of 2.0. 10.7 centimeter flux is 100, 
95, 95, 95, 95, 100, and 100 with a mean of 97.1.

For more information concerning shortwave radio propagation, see 
www.arrl.org/propagation 
<https://arrl.informz.net/z/cjUucD9taT0zNzIwMzkxJnA9MSZ1PTUyNTQ3MzY2NCZsaT00NDUyMzAzMg/index.html> 
and the ARRL Technical Information Service web page at 
www.arrl.org/propagation-of-rf-signals 
<https://arrl.informz.net/z/cjUucD9taT0zNzIwMzkxJnA9MSZ1PTUyNTQ3MzY2NCZsaT00NDUyMzAzMw/index.html>. 
For an explanation of numbers used in this bulletin, see 
www.arrl.org/the-sun-the-earth-the-ionosphere 
<https://arrl.informz.net/z/cjUucD9taT0zNzIwMzkxJnA9MSZ1PTUyNTQ3MzY2NCZsaT00NDUyMzAzNA/index.html>. 
Information and tutorials on propagation can be found at http://k9la.us 
<https://arrl.informz.net/z/cjUucD9taT0zNzIwMzkxJnA9MSZ1PTUyNTQ3MzY2NCZsaT00NDUyMzAzNQ/index.html>.

NNNN

/EX

	

	

	

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