ALERT – Geomagnetic K-index of 4 Alert issued on October 10

An ALERT – Geomagnetic K-index of 4 Alert was issued on October 10, 2025, at 03:02 UTC by NOAA’s Space Weather Prediction Center. The K-index of 4 threshold was reached at 02:59 UTC during the synoptic period of 00:00 to 03:00 UTC. The alert is currently active, indicating unsettled geomagnetic conditions.

According to NOAA SWPC, the area of impact is expected to be primarily poleward of 65 degrees geomagnetic latitude. Potential impacts include weak power grid fluctuations due to induced currents, and aurora may be visible at high latitudes such as Canada and Alaska. These effects are in line with typical conditions for this level of geomagnetic activity.

Review of the latest forecast discussion indicates that quiet geomagnetic field activity was observed in the previous 24 hours. Solar wind parameters showed slight enhancement, with a minor increase in magnetic field strength and solar wind speed, but no significant southward Bz was detected. The current alert corresponds to this elevated, but not storm-level, geomagnetic activity. No recent Earth-directed coronal mass ejections have been identified in available observations.