The United States National Oceanic and Atmospheric Administration (NOAA) has issued an alert for a G4 level geomagnetic storm, classified as severe, that has been impacting the Earth’s magnetic field since the morning of this Tuesday, November 12, 2025. The phenomenon results from a coronal mass ejection (CME) ejected by the Sun on November 11, with charged particles colliding against the planetary magnetosphere at speeds of up to 1,850 kilometers per second. Scientists monitor the event in real time, highlighting risks to technological infrastructures on a global scale.
This disturbance occurs during the peak of solar cycle 25, which increases stellar activity and increases the frequency of similar events. The compression of Earth’s protective magnetic bubble already records Kp indices of 8.5, close to the extreme G5 level. Authorities recommend checks on vulnerable systems to minimize disruptions.
- Northern lights visible in regions such as Florida, Mexico and Argentina, far from the usual polar zones.
- Interference with HF radio transmissions, used by aviation and the navy.
- Possible fluctuations in power grids, similar to the Quebec blackout in 1989.
Solar flare origin
The X5.1 class solar flare, the most powerful recorded in 2025, came from sunspot AR4274, an active region on the Sun’s surface that released energy accumulated in stressed magnetic lines. This eruption occurred around 8am UTC on November 11 and was captured by NASA probes, revealing a cloud of plasma and magnetic fields directed partially toward Earth.
Forecast models indicate that the EMC shock front reached the planet in less than 24 hours, initiating the interaction with the magnetic field.
Real-time monitoring
NOAA experts monitor the Kp index, which measures the intensity of geomagnetic disturbance, with current values at 8.5 and the potential to rise to 9.
The Space Weather Prediction Center records compression of the magnetosphere by more than 30% compared to normal conditions, with solar particles penetrating upper atmospheric layers. This analysis takes place at stations in Boulder, Colorado, where teams operate 24 hours a day to update alerts.
Data from satellites like GOES show peaks in X and ultraviolet radiation, confirming the scale of the event.
A second EMC, of lesser intensity, can combine with the main one, forming a “cannibal EMC” that amplifies the effects, according to computer simulations.
Effects on infrastructure
Electrical networks face risks of voltage variations that activate automatic protections, leading to localized shutdowns in high-latitude areas.tude.
GPS systems record positioning errors of up to 50 meters, affecting air and sea navigation and precision agriculture, where autonomous machines depend on precise signals.
Low-orbit satellites, such as those used for communications and Earth observation, experience temporary signal degradation due to the injection of high-energy electrons.
Telecommunications operators prepare contingencies for failures in high-frequency links, estimated to last hours to days.
Visibility of auroras
The phenomenon alters the ionosphere, allowing solar particles to excite atmospheric gases and generate colored lights visible at mid-latitudes.
Reports confirm auroras in southern US states, such as Pennsylvania and Oregon, in addition to observations in Mexico and Argentina.
In Portugal, images captured show green and red tones in the night sky, a rare spectacle for local observers.
Similar event history
G4 storms occurred in May 2024, when auroras reached southern Brazil, and in April 2025, with visibility in France.
Solar cycle 25, which began in 2019, is expected to peak in July 2025, with 20% of CMEs directed towards Earth generating disturbances above G2.
Records indicate that events in 1859, such as the Carrington Event, caused burning telegrams and global aurorasis, highlighting historical vulnerabilities.
Mitigation Measures
Space agencies coordinate responses to protect orbital assets by adjusting orbits of sensitive satellites.
Power companies test transformers against geomagnetically induced currents, which can damage equipment.
Planes avoid polar routes to reduce radiation exposure, with crews monitoring dosimeters.
Perspectives for the coming days
The storm is expected to persist until November 13, with a probability of 65% for new class M eruptions and 15% for class X from AR4274.
Models predict a gradual decline in the Kp index after the peak, restoring normal conditions within 48 hours.
Amateur observers set up cameras to capture possible residual auroras on subsequent nights.
