G2 – Moderate Geomagnetic Storm Alert issued on May 4

A G2 – Moderate Geomagnetic Storm Alert was issued on May 4, 2026, after the geomagnetic K-index reached 6 at 20:32 UTC. The alert is active for the synoptic period from 18:00 to 21:00 UTC. This event meets the threshold for a moderate geomagnetic storm as defined by NOAA SWPC.

Potential impacts are expected primarily poleward of 55 degrees geomagnetic latitude. Power grid fluctuations can occur, with high-latitude power systems possibly experiencing voltage alarms. Satellite operators may observe orientation irregularities and increased drag on low Earth-orbit satellites is possible. HF radio propagation may experience fading at higher latitudes. Aurora displays may be visible as far south as New York, Wisconsin, and Washington state.

Forecast discussions indicate that solar wind conditions were influenced by a weak negative polarity coronal hole high-speed stream (CH HSS), with no Earth-directed CMEs observed. The geomagnetic field activity was noted as quiet to unsettled prior to this alert, and conditions are expected to gradually diminish in the coming days as CH HSS influences wane.