The fire has burnt over two hundred and twenty thousand acres in California, including forty-nine thousand in Yosemite National Park.
One hundred and eleven buildings, including thirty-one homes, have been lost to the flames.
Forty-five hundred homes and a thousand other buildings lie with a mandatory evacuation area, that is threatened by the blaze.
Winds continue to help the fire expand and drown nearby towns in smoke, making breathing difficult.
However, lower temperatures and higher humidity have aided in battling the fire.
Yosemite National Park has remained opened, the main part of the park lies more than twenty miles away and authorities say that it is not in any danger.
Most worries are focused on the Hetch Hetchy Reservoir and the O'Shaughnessy Dam, which are now less than half a mile from the flames.
San Fransisco gets eighty-five percent of it's water from the reservoir and significant amounts of power from the dam.
City officials say that they have adequate emergency reserves, should the water become reached by the smoke.
They are also doing hourly checks of water quality to ensure that contaminants from the fire are not reaching people's drinking water.
Power supply has already been interrupted, as some power lines have fallen victim to flames.
