Severe and Extreme (G4-G5) Geomagnetic Storms Likely on 12 May 2024 published: Monday, May 13, 2024 12:25 UTC Another series of CMEs associated with flare activity from Region 3664 over the past several days are expected to merge and arrive at Earth by midday (UTC) on 12 May. Periods of G4-G5 (Severe-Extreme) geomagnetic storms are likely?to follow the arrival of these CMEs.??