A partial halo Coronal Mass Ejection, SIDC CME720, was first seen in SOHO/LASCO C2 from around 19:36 UTC on September 12 and visible to the south-south-east in STEREO-A/COR2 at 23:53 UTC. In the plane of the sky, the CME appeared mainly southward directed (principle angle 202 degrees) and slow, with an initial estimated plane-of-sky speed of about 187 km/s and an angular width of about 110 degrees. The most likely source region was located along the 40° south latitude band. Due to its source location and propagation direction, no notable impact on earth is expected.

A halo or partial-halo CME was detected with the following characteristics: t0 | dt0| pa | da | v | dv | minv| maxv| 2026-09-12T22:00:33.567 | 6.0 | 13 | 256 | 1525 | 340 | 502 | 1953 t0: onset time, earliest indication of liftoff dt0: duration of liftoff (hours) pa: principal angle, counterclockwise from North (degrees) da: angular width of the CME (degrees), v: median velocity (km/s) dv: variation (1 sigma) of velocity over the width of the CME mindv: lowest velocity detected within the CME maxdv: highest velocity detected within the CME

Solar flaring activity was low over the past 24 hours, with only C-class flares identified. The largest flare was a C5.8 flare (SIDC Flare 8571) peaking on September 12 at 17:20 UTC, which was produced by SIDC Sunspot Group 952 (NOAA Active Region 4521). A total of 6 numbered sunspot groups were identified on the disk over the past 24 hours, all alpha or beta magnetic configuration. SIDC Sunspot Group 952 (NOAA Active Region 4521) and SIDC Sunspot Group 958 (NOAA Active Region 4530) were the most active regions of the past 24 hours. SIDC Sunspot Group 952 (NOAA Active Region 4521) has turned over the westlimb. A partial halo Coronal Mass Ejection, SIDC CME720, was first seen in SOHO/LASCO C2 from around 19:36 UTC on September 12 and visible to the south-south-east in STEREO-A/COR2 at 23:53 UTC. In the plane of the sky, the CME appeared mainly southward directed (principle angle 202 degrees) and slow, with an initial estimated plane-of-sky speed of about 187 km/s and an angular width of about 110 degrees. The most likely source region was most likely located along the 40° south latitude band. Due to its source location and propagation direction, no notable impact on earth is expected. The long east-westwards elongated southern mid latitude negative polarity coronal hole (SIDC CH 149) continues its crossing of the central meridian. The associated high-speed stream may enhance the solar wind conditions near Earth in the next 24 hours. The northern mid latitude negative polarity coronal hole (SIDC CH 142) continues its crossing of the central meridian. The associated high-speed stream may enhance the solar wind conditions near Earth around September 15. The greater than 10 MeV proton flux remained below the 10 pfu threshold and is expected to remain so for the next 24 hours. The greater than 2 MeV electron flux, as measured by GOES-18 and GOES-19,were mainly slightly above the 1000 pfu alert threshold. The greater than 2 MeV electron flux is expected to remain above the alert threshold initially and may drop below the threshold in case of the high speed stream arrival associated with SIDC CH 149. The 24-hour electron fluence was at moderate levels and is expected to remain at normal to moderate levels over the next 24 hours.

Geomagnetic conditions were quiet to unsettled globally and locally (NOAA Kp 3, K BEL 3), over the past 24 hours. Enhanced geomagnetic conditions are possible in the next 24 hours due to the possible arrival of the high-speed stream associated with SIDC Coronal Hole 149 which may lead to active conditions, with K values possibly reaching 4. Further enhanced geomagnetic conditions may be expected around September 15, following the possible arrival of the high-speed stream associated with SIDC Coronal Hole 142, with K values possibly reaching 5 . Solar wind conditions near Earth were slow over the past 24 hours, with the solar wind speed around 380 km/s, the interplanetary magnetic field varying between 4 and 7 nT, and the minimum Bz reaching about -6 nT. Fast solar wind conditions are possible in the next 24 hours due to the possible arrival of the high-speed stream associated with SIDC Coronal Hole 149. Further enhanced solar wind conditions may be expected around September 15, following the possible arrival of the high-speed stream associated with SIDC Coronal Hole 142.