The fires have burnt at least 24,000 hectares (59,000 acres) of land on the islands of Gran Canaria and Tenerife.
Spain's Environment Minister Cristina Narbona called a state of "maximum alert" and ordered more water-bombing planes to help douse the fires.
Local officials said that 5,200 people had been taken to safety on Gran Canaria and at least 5,700 people were evacuated from homes in Tenerife as the four-day blaze continued to burn.