Division Chief Wayne Connor said the fire "should be pushing 100 percent by the end of the day" and is expected to be fully contained Wednesday.
"People are probably going to see some smoke and flames throughout the day, but those are from fire operations," Connor said. "We'd rather burn it on our terms than otherwise."
The fire has ripped through 4,089 acres since igniting Saturday near Wild Horse Valley Road in Napa County. It quickly spread through dry grass, oak trees and brush toward the area of Lake Madigan in Solano County.
The blaze prompted mandatory evacuations. However, residents have since been allowed to return to their homes on Twin Sisters, Gordon Valley, Wooden Valley, Suisun Valley and Green Valley roads, as well as Joyce Lane, Connor said.
Some roads are only accessible to residents who present a valid form of identification.
Conner said Cal Fire resources are transitioning from the Wild Fire to the Walker Fire in Lake County, which has burned an estimated 8,600 acres with the potential of growing to 10,000 to 15,000 acres.
The Wild Fire destroyed one outbuilding and one firefighter suffered heat exhaustion while combating the flames.
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MORE: ABC7's Bay Area wildfire resource guide and safety tips
MAP: Google Reference Map of California's Early Season Fires
(From the Governor's Office of Emergency Services).