G1 – Minor Geomagnetic Storm Alert issued on May 4, 2026

A G1 – Minor Geomagnetic Storm Alert was issued for May 4, 2026, after the Geomagnetic K-index reached a value of 5. The alert was announced by the NOAA Space Weather Prediction Center at 19:51 UTC and covers the synoptic period from 18:00 UTC to 21:00 UTC. This alert indicates minor geomagnetic storm conditions are present.

According to the alert details, the primary area of impact is poleward of 60 degrees geomagnetic latitude. Potential effects include weak power grid fluctuations, minor impact on satellite operations, and the possibility of aurora sightings at high latitudes such as the northern tier of the United States, including regions like northern Michigan and Maine. These impacts correspond to the NOAA G1 – Minor classification for geomagnetic storms.

The latest forecast discussion describes recent solar wind parameters reflecting weak negative polarity coronal hole high-speed stream influences, with a minor increase in total field observed early on May 4. Solar wind speeds decreased during the period and no Earth-directed coronal mass ejections were observed. The geomagnetic field activity was quiet to unsettled prior to the alert, with continued minor influences expected over the coming days.