Major Solar Storm Causes Radio Blackouts Across Europe and Africa
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A powerful geomagnetic storm has been underway since the night of November 11–12, reaching G4 intensity—one step below the highest G5 level, according to the U.S. National Oceanic and Atmospheric Administration (NOAA) Space Weather Prediction Center.
The storm was triggered by the arrival of two consecutive coronal mass ejections (CMEs)—large expulsions of plasma from the Sun. One of these CMEs was accompanied by the strongest solar flare of 2025 to date, an X5.1-class event. The sudden flare caused radio blackouts across Europe and Africa, disrupting high-frequency communications on the Sun-facing side of the Earth.
“The storm has been ongoing for several hours and began very abruptly,” said Mauro Messerotti, Professor of Space Meteorology at the University of Trieste. “It was caused by two CMEs that arrived in quick succession on November 11, and a third CME is expected. We will have to monitor how the situation develops.”
The flares and CMEs originated from sunspot AR4274, which has been highly active in recent weeks and is one of the most prolific producers of solar flares in the current solar cycle. “The sunspot has steadily grown and exhibits extremely complex magnetic structures,” Messerotti explained. “It is a highly unstable reservoir of energy.”
The storm has produced striking auroral displays even at Italian latitudes, with images captured in Plan de Corones in Trentino-Alto Adige, in the southeastern Alps, showing vivid colors in the night sky.
Beyond the visual spectacle, G4-class geomagnetic storms can pose serious challenges to infrastructure. They have the potential to disrupt electrical grids, alter the orientation of satellites in orbit, and interfere with radio communications and satellite navigation systems.
