SB PROP @ ARL $ARLP041
ARLP041 Propagation Forecast
ZCZC AP41
QST de W1AW
Propagation Forecast Bulletin 41 ARLP041
From ARRL Headquarters
Newington, CT October 9, 2026
To all radio amateurs
SB PROP ARL ARLP041
ARLP041 The ARRL Solar Report
NOAAís Space Weather Prediction Center has issued a G2 (moderate)
Geomagnetic Storm Watch for tomorrow, October 9. It is associated with a coronal mass ejection (CME) that left the sun on October 6. It says the effects should be minor, with mainly manageable effects to some technological infrastructure. The aurora may become visible over some northern and upper Midwest states from New York to Idaho. Additional M-class (minor-moderate) solar flares are expected through October 9, otherwise solar activity is expected to remain at low levels.
The declining sunspot cycle will keep 10 and 12 meters pretty quiet for DX, except for north-south openings and occasional sporadic-E. DX opportunities should be better on 17 and 15 meters in the coming week, with the solar flux above 100 for the entire period (see daily predictions below). Twenty meters will continue being the workhorse DX band, while 30, 40, 60, and 80 meters will be at their best during hours of darkness. Many stations in remote locations will be starting to tune up their equipment for the CQ World Wide SSB DX Contest on October 24-25, so listen for
exotic call signs and unanticipated band openings as they test and tweak their setups.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, October 8, 2026, by F. K. Janda, OK1HH:
The decline in solar activity, which had already been on the horizon in August, occurred during the third decade of September and in the first days of October. Then, as if by magic, on October 5, active region NOAA AR 4549 appeared in the center of the solar disk; it grew rapidly and had the right magnetic configuration to trigger energetic flares. It is therefore no surprise that shortly after midnight UT on October 6, it became the source of two moderately strong flares, accompanied by coronal mass ejections
(CMEs). Based on the speed of the particle clouds heading toward Earth, a geomagnetic disturbance can be expected on October 9. If it begins during daylight hours, we can expect a positive phase to develop. Over the following weekend, we should expect a negative phase.
The decline and subsequent increase in solar activity over the past few weeks can be seen as a precursor to heightened solar activity over the next 2ñ3 months. After that, solar activity will continue to decline toward the minimum of the 11-year cycle. The Predicted Planetary A Index for October 9 to October 15 is 5, 5, 10, 8, 8, 8, and 5 with a mean of 7.0. The Predicted
Planetary K Index is 2, 2, 3, 3, 3, 3, and 2 with a mean of 2.6. 10.7 centimeter flux is 92, 92, 90, 90, 95, 100, and 105 with a mean of 94.9.
For more information concerning shortwave radio propagation, see www.arrl.org/propagation and the ARRL Technical Information Service web page at www.arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere. Information and tutorials on propagation can be found at http://k9la.us.
Also, check this: ''Understanding Solar Indices'' from September 2002 QST. https://bit.ly/3Rc8Njt
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