In Aguiar da Beira, water bombing aircraft swept overhead while ground crews worked in difficult conditions.
In Arganil, Coimbra district, 890 firefighters were deployed after flames spread to neighbouring municipalities, forcing evacuations and surrounding the historic village of Piódão.
Further north in Trancoso, hundreds of firefighters faced strong winds and mountainous terrain that hindered containment efforts.
Authorities remain on high alert until Friday, citing extreme wildfire risk driven by high temperatures, dry conditions, and gusty winds.