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  • Weekly Highlights of Solar and Geomagnetic Activity, 21 - 27 September 2026

    From SWPC.Webmaster@SWPC.Webmaster@noaa.gov to rec.radio.amateur.dx,rec.radio.amateur.space,rec.radio.shortwave,rec.radio.info on Mon Sep 28 13:00:04 2026
    From Newsgroup: rec.radio.amateur.space

    :Product: Weekly Highlights and Forecasts
    :Issued: 2026 Sep 28 0221 UTC
    # Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
    # Product description and SWPC contact on the Web
    # https://www.swpc.noaa.gov/content/subscription-services
    #
    # Weekly Highlights and Forecasts
    #
    Highlights of Solar and Geomagnetic Activity
    21 - 27 September 2026

    Solar activity was at low levels throughout the summary period.
    Region 4534 (N11, L=075, class/area=Dai/050 on 22 Sep) produced the
    strongest flare of the period, an impulsive C3.1 flare at 26/1655
    UTC. There were 13 other numbered active regions recorded on the
    visible disk this week but they all remained relatively simple and
    absent of any significant activity. No Earth-directed CMEs were
    observed in available coronagraph imagery.

    No proton events were observed at geosynchronous orbit.

    The greater than 2 MeV electron flux at geosynchronous orbit reached
    high levels on 23 Sep, and 26-27 Sep due to influence from a
    positive polarity CH HSS.

    Geomagnetic field activity was at quiet levels from 21-23 Sep. A CIR
    ahead of a positive polarity CH HSS caused active levels over 24-27
    Sep. Total magnetic field strength reached 15 nT during the CIR on
    24 Sep, with the Bz component rotating as far south as -12 nT. Solar
    wind speeds steadily increased from below 300 km/s on 23 Sep to a
    peak of ~525 km/s by 25 Sep. Both total magnetic field strength and
    solar wind speeds gradually declined during the waning phase of the
    coronal hole HSS over 26-27 Sep.

    Forecast of Solar and Geomagnetic Activity
    28 September - 24 October 2026

    Solar activity is likely to continue at very low to low levels
    throughout the outlook 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 from 28 Sep-03 Oct, 05 Oct-11 Oct, and
    23-24 Oct due to anticipated influence from multiple, recurrent, CH
    HSSs. Moderate levels are likely over the remainder of the outlook
    period.

    Geomagnetic field activity is likely to reach G1 (Minor) geomagnetic
    storm levels on 22 Oct. Active conditions are likely over 04-06 Oct,
    21 Oct, and 23-24 Oct. Unsettled conditions are likely over 07-08
    Oct and 11-14 Oct. All increases in geomagnetic activity are
    associated with anticipated influence from multiple, recurrent,
    coronal hole HSSs. The remainder of the outlook period is likely to
    be at mostly quiet levels.

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