Around 1,000 hectares (2,500 acres) have so far been destroyed in the fire, which erupted Saturday in the western municipality of Artenara near the provincial capital of Las Palmas.
Some 1,000 residents evacuated overnight have not yet been allowed to return to their homes, emergency services said in a statement on Sunday.
Police said they had detained a man for allegedly starting the fire by using welding equipment.
Fire fighters battling the flames seemed to have the upper hand by Saturday evening but a change in wind direction worsened the situation overnight, Canary Islands president Angel Victor Torres told Spanish radio COPE on Sunday.
More than 200 fire fighters, including an emergency military unit deployed only for worst-case scenarios, were trying to bring the situation under control, he added.
Water bomber planes
Ten water bomber planes and helicopters have been mobilised to help contain the fires before the sun went down and winds picked up again.
He said three areas remained of major concern, including one where the fire proved particularly difficult.
The mountainous landscape of the volcanic island, a part of which was declared a UNESCO world heritage site in July, has been complicating matters, Torres said.
Spain, the world's second most popular tourist destination, is frequently plagued by huge forest fires because of its arid climate in summer.