G2 – Moderate Geomagnetic Storm Alert issued on October 18

A G2 – Moderate Geomagnetic Storm Alert was issued on October 18, 2025, following the threshold exceedance of a geomagnetic K-index of 6. The alert is valid for the synoptic period from 18:00 to 21:00 UTC, indicating ongoing moderate geomagnetic storm conditions.

Potential impacts are expected primarily in regions poleward of 55 degrees geomagnetic latitude. Power grid fluctuations may occur, and high-latitude power systems could experience voltage alarms. Satellite operators may encounter orientation irregularities and increased atmospheric drag on low Earth-orbit spacecraft. HF (high frequency) radio propagation may be degraded at higher latitudes. Aurora sightings are possible as far south as New York, Wisconsin, and Washington state.

According to the latest NOAA Space Weather Prediction Center discussion, the storm is likely triggered by a glancing blow from coronal mass ejections (CMEs) that left the Sun between October 13 and 15. Forecasts anticipated geomagnetic enhancements on October 18 due to these CME influences, with a transition into a negative polarity coronal hole high-speed stream expected on October 19.