Spain’s national weather agency warned of extreme fire risk in most of Spain, including where the largest blazes were burning in the north and west.

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 fires in Spain this year have burned 158,000 hectares or 610 square miles, according to the European Union’s European Forest Fire Information System. That is an area roughly as big as metropolitan London.