The fires, which quickly spread through the provinces of Palermo, Agrigento, Trapani and Messina, broke out at the same time, suggesting a criminal motive, investigators told Ansa.
Sicily President Rosario Crocetta told La Repubblica that he believed organized crime was behind the fires.
“How do you explain a blazing fire in Cefalù last night (Wednesday), when the temperature was 24 degrees?”, he said.
“Of course, the heat and wind then play their part. I do not have proof, but I suspect criminals were responsible because they always affect the most valuable areas around Palermo."
Some of the fires were still burning on Friday morning along Italy's eastern coast, affecting also the Aeolian islands as the sirocco fanned the flames, and six Canadair planes are still in action, Ansa reported.
Some 250 firefighters are working to extinguish the fires. The wind had dropped by Friday, making the job easier.
Among the most affected areas was the popular tourist spot, Cefalù, a historic coastal city. The fires damaged several homes, hotels and two seafront bars as flames reached the coastline.
In Poggio Maria, close to Cefalù, a girl was rescued from a burning villa, while 50 nursery school children were treated for smoke inhalation.
“The fires didn't just start themselves,” said Fabrizio Curcio, the head of Italy's civil protection.
“I can't say whether or not is it arson, but they are not created themselves, especially if they start in different places.”