G1 – Minor Geomagnetic Storm Alert issued on April 21, 2026

A G1 – Minor Geomagnetic Storm Alert was issued for April 21, 2026, after the geomagnetic K-index reached a value of 5 at 01:48 UTC. The alert covers the synoptic period from 00:00 to 03:00 UTC and remains active as of the latest update from NOAA SWPC.

According to NOAA, the area of impact is primarily poleward of 60 degrees geomagnetic latitude. Weak power grid fluctuations are possible, and there may be minor impacts on satellite operations. Additionally, auroras may become visible at high latitudes, including the northern tier of the United States such as northern Michigan and Maine.

The G1 – Minor Geomagnetic Storm conditions were triggered by enhanced solar wind streams originating from a coronal hole high-speed stream (CH HSS). Sustained periods of southward-directed interplanetary magnetic field (negative Bz) contributed to geomagnetic field disturbances, elevating activity from quiet to G1 (Minor) storm levels. Solar wind speeds increased to around 570 km/s during the reporting period before stabilizing. Enhanced solar wind conditions are expected to weaken, with mostly quiet to unsettled geomagnetic conditions forecast on April 21 as the CH HSS influence diminishes.