Alert – Geomagnetic K-index of 4 Alert issued on June 11, 2026

A Geomagnetic K-index of 4 Alert was issued by the NOAA Space Weather Prediction Center on June 11, 2026. The alert became active at 18:55 UTC and is valid for the synoptic period between 18:00 and 21:00 UTC. The alert remains active as of the latest update.

According to NOAA SWPC, this alert primarily affects areas poleward of 65 degrees geomagnetic latitude. Weak power grid fluctuations are possible in these regions. Additionally, aurora may be visible at high latitudes, including Canada and Alaska.

The current geomagnetic activity has been triggered by enhanced solar wind conditions expected due to a corotating interaction region (CIR) preceding the onset of a negative polarity coronal hole high speed stream (-CH HSS) on June 11. Background solar wind parameters were reported leading up to the alert period, with persistent solar wind effects anticipated through June 13, 2026.