The Portuguese Institute for Sea and Atmosphere (IPMA) describes the phenomenon as a column of air with upward, rotating motion that can extend to several hundred metres. Unlike tornadoes, which develop from storm systems, these whirlwinds occur on clear days because of intense ground heating and a sharp temperature difference with the air in the layers above.

The visual effect of the phenomenon can be linked to the period following the forest fire, which started on 14 August in the Ventuzelos area and had spread from the municipality of Boticas, leading to hundreds of emergency personnel being mobilised and a large area of forest being consumed before the fire could be brought under control.