Strong (G3) #GeomagneticStorm WATCH Valid for 09 Dec 2025
published: Sunday, December 07, 2025 04:42 UTC
A full-halo coronal mass ejection (#CME), associated with an M8.1 flare from Region 4299 at 20:39 UTC on 06 December, is expected to impact Earth early to midday on 09 December, potentially causing periods of G3 (Strong) geomagnetic storming.
Strong Geomagnetic Storm WATCH Valid for 09 December G3
WHAT: A CME is expected to arrive at Earth on 09 December and lead to increased geomagnetic field activity.
EVENT:
A coronal mass ejection (CME) is an eruption of solar material and magnetic fields. When they arrive at Earth, a geomagnetic storm can result. Watches at this level are infrequent, but not uncommon.
EXPECTATION:
A CME is anticipated to arrive at Earth early to midday on 09 December causing elevated geomagnetic field activity, and dependent upon the orientation of the embedded magnetic field, potential exists for G3-Strong storm levels.
EFFECTS:
Limited, minor effects to some technological infrastructure possible, but usually mitigatable. The aurora may become visible over many of the northern states and some of the lower Midwest to Oregon. The general public should consider monitoring our webpage for the latest information and updates.
https://www.swpc.noaa.gov/news/strong-g3-geomagnetic-storm-watch-valid-09-dec-2025
#CMEs #SpaceWeather #SolarFlares #G3