G1 – Minor Geomagnetic Storm Watch issued for September 15 and 16, 2026

A G1 – Minor Geomagnetic Storm Watch was issued for September 15 and 16, 2026. According to the alert released by NOAA’s Space Weather Prediction Center, the highest storm level predicted is G1 – Minor for both days, and conditions are forecast to remain below G1 on September 17. This Watch supersedes all previous watches currently in effect.

Potential impacts from this event are forecast to affect areas primarily poleward of 60 degrees Geomagnetic Latitude. Possible effects include weak power grid fluctuations due to induced currents and minor impacts on satellite operations. Auroras may be visible at high latitude locations, including the northern tier of the United States such as northern Michigan and Maine.

The triggering solar event is attributed to influences from a negative polarity coronal hole high speed stream (CH HSS), which is anticipated to persist through September 16. The geomagnetic field is expected to be unsettled to active, with chances for isolated G1 – Minor periods on September 15 and increasing likelihood on September 16 as another high speed stream becomes geoeffective. No significant flares or coronal mass ejections directly connected to this watch were identified in the latest forecast discussion.