Firefighters in Spain, Portugal and Greece battled ongoing wildfires Friday, an important religious holiday in all three countries, as persistent hot, dry conditions challenged efforts to contain the blazes.

The scale of this summer’s wildfires has prompted unprecedented requests for help from the European Union’s civil protection mechanism. Spain, for the first time, asked for firefighting aircraft from EU partners.

Spain on Thursday mourned its third wildfire death this week and Greece began beating back a blaze threatening its third-largest city as an unrelenting heatwave stoked tinderbox conditions in southern Europe.