G1 – Minor Geomagnetic Storm Alert issued on October 18

A G1 – Minor Geomagnetic Storm Alert was issued on October 18, 2025, following detection of a geomagnetic K-index of 5. The alert is active for the synoptic period from 06:00 to 09:00 UTC, indicating enhanced geomagnetic activity and the potential for minor storm conditions.

Potential impacts from this G1 – Minor event are expected primarily poleward of 60 degrees geomagnetic latitude. Weak power grid fluctuations may occur, and minor impacts to satellite operations are possible. The aurora might be visible at high latitudes, including the northern tier of the United States, such as northern Michigan and Maine.

According to the official forecast discussion, the geomagnetic activity appears to be triggered by a glancing blow from coronal mass ejections (CMEs) that departed the Sun between October 13 and 15. These CMEs are predicted to cause unsettled to active geomagnetic conditions, with a chance for G1 – Minor storming through early October 19. The main impact is expected to result from CME influences, with further activity possible as the Earth enters a negative polarity coronal hole high speed stream on October 19.