Severe Earth Geomagnetic Storm Watch in Effect | NOAA

Severe Earth Geomagnetic Storm Watch in Effect | NOAA

A G4 (Severe) Spaceweather Watch has been posted for Nov. 12, 2025 by the U.S. National Oceanic and Atmospheric Administration (NOAA). The recent, fast coronal mass ejection (CME) will arrive at about midday and there is potential for a G4 electromagnetic storm. Coronal mass ejections are huge bubbles of gas threaded with magnetic field lines that are ejected from the Sun over the course of several hours.

Today's X5-class solar flare from sunspot 4274 hurled a fuisillade of energetic protons toward Earth. Particles are so powerful, they are penetrating the atmosphere all the way to the ground. "This is a very significant event," says Professor Clive Dyer of the Surrey Space Centre. "Neutron monitors around the world are detecting it."

This is called a Ground Level Event (GLE). GLEs of this magnitude are rare; they happen only once or twice every solar cycle. "This one is comparable to the GLE of Dec. 13, 2006," says Dyer. That makes it a ~20-year event.

Geomagnetic Storm Watches in Effect, to include G4 (Severe) potential for November 12, 2025. The current list of Watches include: Nov 11 G2 (Moderate); Nov 12 G4 (Severe); and Nov 13 G3 (Strong). These Watches are in response to potential geomagnetic storm effects related to coronal mass ejections (CME) that have erupted from the Sun over the past several days. These events include CME activity from November 9 through the early morning of November 12. The most recent CME occurred early on Nov. 12 and is the most energetic and fastest of the CMEs. This CME was associated with an X5.1 solar flare (R3; Strong) that peaked at 1004 UTC (5:04 am EST) on Nov 11. This CME is also associated with a moderate level solar radiation storm (S2) that is currently in progress. The forecast is tough due to this latest CME’s predominant ejecta aimed north and ahead of Earth’s orbit; additionally the previous CMEs are in the mix and anticipated to have some Earth-arrival influences prior to the Nov. 12 CME arrival. 

Confidence in an Earth-component to the most recent CME is high, while timing has a moderate level of certainty. As always with these events, the intensity of the CME will not be know with better certainty until it arrives 1 million miles from Earth and is observed by the solar wind observatories at that location. It is at that point that any needed Warning decisions can be made by Space Weather Prediction Center (SWPC) forecasters. So, for now, SWPC believes there is a potential for G4 levels upon CME arrival and/or as the CME passage progresses. 

For updates, visit: 
http://spaceweather.gov
https://swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction 

Credit: National Oceanic and Atmospheric Administration (NOAA)
Release Date: Nov. 11, 2025

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