Portugal's government is taking the rare step of decreeing a state of public calamity before a forecast rise in temperatures that authorities fear will worsen a spate of wildfires.

Prime Minister Antonio Costa's office says in a statement that he will meet with heads of the emergency services, including the armed forces, on Friday to prepare for a weekend rise in temperatures to around 40 C (104 F).

Decreeing a public calamity allows authorities to mobilize emergency assets and quicken reaction times.

Portugal has been fighting woodland blazes for weeks, including one in June that killed 64 people.

The government said Thursday the most worrying areas are in the north and center of the country, as well as western parts of the Algarve on the southern coast.