The interior ministry said about 4,500 people had already been evacuated and another 10,000 might need to be moved.
Valparaiso is still recovering from a forest fire last April that killed 15 people, injured more than 500 and destroyed nearly 3,000 homes.
The fire began at an illegal garbage dump on Friday afternoon, officials said, and spread quickly fanned by strong winds.
By late Friday, Chile`s Emergency Office estimated that about 300 hectares (740 acres) had been affected.
Emergency crews battled through the night to keep the flames from reaching residential districts in Valparaiso.
Three firefighters have been injured so far and a 67-year-old woman died of cardio-respiratory causes, the interior ministry said.
Valparaiso`s poorest areas, often made up of little more than wooden huts, were worst hit by last year`s devastating fire.
Entire neighbourhoods were razed to the ground and many of those who died were found in the burned-down homes they had refused to leave.
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