Over 40 fires remained active on Tuesday, according to local media, with four confirmed deaths and thousands of residents evacuated.
The worst affected areas are León and Zamora in Castile and León, and Ourense in Galicia, where blazes have spread into neighbouring Lugo.
Water-bombing aircraft flew overhead, and residents joined firefighters battling flames metres from their doorsteps.
Crews from across Europe, including Estonia, France, Italy and Slovakia, reinforced Spanish teams as strong winds complicated efforts.
