The weather event stretched from Empordà to Xàbia, including Ibiza, where flight operations were affected. In Catalonia, several roads experienced difficult driving conditions for hours. This phenomenon, known as advection fog, occurs when moist sea air moves over a colder land surface, causing water vapor to condense into tiny droplets.

Meteorologists point to the current anticyclone as a key factor, as it prevents humidity from dispersing and creates a thermal inversion. The fog typically dissipates once the sun warms the ground and wind begins to break the stagnant air layer, as seen later in the day across the Spanish coast.