Overview
- The U.S. Space Weather Prediction Center put out a G3 (strong) geomagnetic storm watch for June 4–5 after a sequence of two M‑class flares and one X‑class flare from solar region 4455 produced multiple coronal mass ejections.
- Models and satellite observations show the combined CMEs were expected to begin affecting Earth in mid‑afternoon EDT on June 4 with activity continuing into the early hours of June 5.
- A G3 storm can cause temporary technical impacts such as satellite surface charging, intermittent GPS and radio navigation errors, and voltage management actions or alarms on power grids.
- The storm raises the chance of visible auroras much farther south than usual, with forecasts saying they could be seen in parts of Illinois under dark skies and clear northern horizons.
- NOAA and NASA are monitoring real‑time solar wind and magnetosphere data and will update forecasts as in‑situ measurements arrive; the event fits the Sun’s heightened activity near its 11‑year maximum.