SB PROP @ ARL $ARLP040
ARLP040 Propagation Forecast
ZCZC AP40
QST de W1AW
Propagation Forecast Bulletin 40 ARLP040
From ARRL Headquarters
Newington, CT October 2, 2026
To all radio amateurs
SB PROP ARL ARLP040
ARLP040 The ARRL Solar Report
Solar activity is expected to remain at low levels in the coming days, according to NOAAís Space Weather Prediction Center, with a slight chance of a minor to moderate solar flare (coronal mass ejection, or CME). One CME observed on September 28 may cause the Earthís geomagnetic field to reach minor storm levels on October 2. Another flare observed
on September 30 is expected to deliver a weak glancing blow to Earth on October 4.
Australiaís Space Weather Forecasting Centre predicts normal to normal-fair HF propagation in the middle latitudes in coming days, with the degradation due to anticipated geomagnetic activity.
The W3LPL Propagation Forecast from the Daily DX suggests that the low bands are your best bet for DXing right now, as the sunspot cycle continues to decline, although 20 meters still offers good DX opportunities. Long-distance propagation on 10 and 12 meters is generally poor, with good openings on 17 and 15 meters when the solar flux index is 100 or higher
(itís currently hovering right around 100; see below). Good DX conditions can be expected on 20 meters throughout the day and into the night, says W3LPL, with 30, 40, and 80 meters offering excellent DX during hours of darkness.
Weekly Commentary on the Sun, the Magnetosphere, and the Earths Ionosphere, October 1, 2026, by F. K. Janda, OK1HH:
Solar activity remains mostly low, while the only two sunspot groups are approaching the western limb of the solar disk. If they disappear and no other sunspots appear, we will see our fifth spotless day of the year. Nevertheless, there have been solar flares, the largest of whichóa C8.6-class flareóreached its peak at 2:46 UTC on September 30 in region NOAA 4535. It was accompanied by Type II and Type IV radio emissions; however, this CME is expected to miss Earth. However, Earth will most likely not escape the intensified solar wind from SIDC coronal hole No. 179, which is expected to hit Earth on October 3.
Solar activity is likely to remain low throughout the first half of October. The geomagnetic field will probably be mostly quiet. Propagation conditions should therefore be relatively stable with a regular diurnal cycle, though with limited openings on the shortest shortwave bands.
The Predicted Planetary A Index for October 2 to October 8 is 5, 5, 12, 15, 12, 10, and 8 with a mean of 9.6. The Predicted Planetary K Index is 2, 2, 4, 4, 4, 3, and 3 with a mean of 3.1. 10.7 centimeter flux is 100, 95, 90, 91, 91, 92, and 93 with a mean of 93.1.
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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