624
FXXX06 KWNP 280256
WEKHIL

:Product: 7-day Space Weather Highlights
:Issued: 2026 Sep 28 0221 UTC
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#                7-day Space Weather Highlights
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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.