Authorities said that 3,000 firefighters and 30 aircraft were battling active blazes.
An estimated 30 people have been injured after several forest fires raged across central Portugal.
More than 3,000 firefighters and 30 aircraft battled active blazes, the country's Civil Protection Agency said on Sunday.
Authorities said 12 firefighters and 17 civilians required medical assistance to treat minor injuries such as smoke inhalation.
Portugal’s government has declared a state of heightened alert that will run through Friday.
The wildfires are coming as the country is enduring a heat wave with temperatures expected up to 43 degrees Celsius. In June, 96% of the southern European country was classified as being in either “extreme” or “severe” drought.
Prime Minister António Costa postponed his plans to visit Mozambique this week “in view of the weather forecasts that indicate a very serious worsening of the risk of rural fires.”
Portuguese President Marcelo Rebelo de Sousa likewise cancelled a scheduled trip to the UN Economic and Social Council in New York.
The European Union has also activated its firefighting air fleet assistance programme that allows member nations to share resources to help Portugal.
The bloc says climate change has the continent facing one of its hardest years for natural disasters such as droughts and wildfires.
In 2017, more than 100 people were killed as wildfires raged out of control across Portugal.