Northern lights in Catalonia: the sky will turn green this October

Between 20 and 29 October 2025, astronomers expect the northern lights to become visible in Spain again, and Catalonia will be one of the privileged settings from which to watch this phenomenon that, until recently, seemed reserved for Iceland or Norway.

Although it will not reach the intensity of the spectacle recorded in May 2024, the phenomenon promises brushstrokes of green, red and violet light that could be seen on the Costa Daurada, especially in areas of Tarragona with clear skies and low light pollution.

The phenomenon is caused by solar particles colliding with the Earth's magnetosphere which, when they react with atmospheric gases, create luminous curtains dancing over the horizon. On this occasion, forecasts also point to possible sightings in Galicia, Navarre or the Ebro Valley, where the phenomenon could recur faintly.

To increase the chances of seeing it, experts recommend moving away from urban centres and seeking out high, dark places. If weather conditions cooperate, October could give Catalans an unprecedented picture: the Mediterranean beneath a polar sky.