=================================== Weekly Space Weather Highlights =================================== Highlights of Solar and Geomagnetic Activity 18 - 24 September 2023 Solar activity was at low levels on 18 Sep, moderate levels on 19, 22-24 Sep, and high levels on 20-21 Sep. In total, ten R1 (Minor) events and two R2 (Moderate) events were registered throughout the period. Region 3435 (N10, L=102, class/area=Dki/300 on 24 Sep) produced two M8 flares at 20/1419 UTC and at 21/1254 UTC, along with four R1 events over 19-22 Sep. CMEs associated with flare activity on 20-21 Sep were predicted to arrive on 23 Sep, but ultimately missed. A CME associated with a long-duration M1.2 flare at 22/0336 UTC from Region 3435 resulted in an Earth-directed CME that arrived on 24 Sep. A CME associated with a filament eruption centered near N36W05 at 22/0645 UTC was modelled and was predicted to arrive on 24-25 Sep. Region 3443 (N28, L=147, class/area=Dki/260 on 23 Sep) produced four R1 events on 22 and 24 Sep. A CME associated with flare activity from Region 3435 at 22/2233 UTC was modelled and is likely to arrive on 26 Sep. No proton events were observed at geosynchronous orbit, though a minor enhancement was observed on 24 Sep. The greater than 2 MeV electron flux at geosynchronous orbit reached moderate levels on 18 Sep, and high levels on 19-24 Sep. Geomagnetic field activity reached G1 (Minor) storm levels on 18 Sep due to residual effects of a CME from 14 Sep. G3 (Strong) storm levels were observed on 19 Sep, and active conditions were observed on 20 Sep, due to the passage of a CME from 16 Sep. Quiet to unsettled conditions were observed over 21-23 Sep. G2 (Moderate) storms were observed on 24 Sep due to the arrival of a CME from 22 Sep. Forecast of Solar and Geomagnetic Activity 25 September - 21 October 2023 Solar activity is expected to be low to moderate with M-class flare activity likely through much of the period. No proton events are expected at geosynchronous orbit. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 25-28 Sep, and moderate levels throughout the remainder of the outlook period. Geomagnetic field activity is expected to reach G1-G2 (Minor-Moderate) storm levels on 25 Sep due to the passage of a CME from early on 22 Sep. Active levels are expected on 26 Sep due to residual CME effects in addition to the predicted glancing-blow arrival of a CME from late on 22 Sep. Quiet conditions are expected to prevail throughout the remainder of the period.