ALERT: Geomagnetic K-index of 4 Alert issued on June 5

A Geomagnetic K-index of 4 Alert was issued on June 5, 2026, by the NOAA Space Weather Prediction Center. The alert threshold was reached at 12:53 UTC, and the alert is valid for the synoptic period from 12:00 to 15:00 UTC. An active warning is currently in effect.

Potential impacts are expected primarily in areas poleward of 65 degrees geomagnetic latitude. Weak power grid fluctuations may occur due to induced currents. Additionally, auroras may be visible at high latitudes, including regions such as Canada and Alaska.

According to the latest forecast discussion, this alert was triggered as geomagnetic field conditions increased in response to multiple coronal mass ejection (CME) arrivals from June 3. Solar wind parameters escalated early on June 5, including a rapid rise in wind speeds and magnetic field strength, leading to enhanced and disturbed conditions. Geomagnetic activity is forecast to remain elevated with possible further storming through early June 6 before subsiding toward background levels by June 7.