Firefighters in Northern California have partially contained a stubborn blaze that has forced hundreds of residents to evacuate areas west of Sacramento, although dry conditions and wind gusts are hampering efforts to stop the spread, authorities said on Wednesday.

The National Weather Service said it expects wind gusts of up to 25 miles per hour (40 kph) in rural Yolo and Napa counties, west of the state capital, where rough terrain is already complicating efforts to battle the wildfire that broke out Saturday.

A force of almost 2,900 firefighters widened its containment lines around the so-called County Fire to 25 percent from 15 percent on Tuesday, the California Fire authority said.