Portugal has called on the EU to help extinguish the wildfires that have destroyed 140,000 hectares of forest and farmland across the country.
Help is on its way from a number of EU countries
Interior Minister Antonio Costa acknowledged that Portugal could not cope without help from abroad.
Spain and France were sending aircraft on Sunday, and help from Italy and Germany is due to arrive on Monday.
Some 3,000 fire fighters, soldiers and police are tackling more than 20 fires, made worse by hot weather and wind.
The fires have so far killed at least 11 firefighters and four civilians, according to AP news agency.
"This is one of the worst years we've had for fires recently," Mr Costa said.
"We cannot overlook the serious effects of the drought we're undergoing and help is now needed."
Two Canadair planes were due to arrive from France on Sunday afternoon, and more planes are expected to be sent from Spain, which is also suffering from wildfires.
Another Canadair plane from Italy, and two German helicopters are due to arrive on Monday.
The Portuguese request was made to the European Commission, which has a special unit to co-ordinate member countries in tackling emergencies.
Portugal is suffering its worst drought for decades.