Alert – Geomagnetic K-index of 4 Alert issued on April 30

A Geomagnetic K-index of 4 Alert was issued by the NOAA Space Weather Prediction Center on April 30, 2026. The alert was triggered at 20:35 UTC, covering the synoptic period from 18:00 to 21:00 UTC. This alert signifies increased geomagnetic activity but does not reach the threshold for a G1 – Minor Geomagnetic Storm.

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

According to the latest forecast discussion issued on April 30, 2026, the onset of a negative polarity coronal hole high speed stream (-CH HSS) is anticipated by mid-April 30 as the main triggering event for these active conditions. No Earth-directed coronal mass ejections have been observed. The geomagnetic field was quiet prior to this alert, with unsettled to active conditions expected to continue as the high speed stream influences persist through May 1, 2026.