Fire-starting lightning and erratic winds threaten effort to tame wildfires in US west

Weather expected to increase fire activity in California, while in Colorado fires crept close to homes near Denver

Firefighters battling California's largest wildfire of the year are preparing for treacherous conditions entering the weekend when thunderstorms could unleash fire-starting lightning and erratic winds that could erode progress made over the past week.

And in Colorado, a wildfire burning in the heavily populated Front Range region has burned dozens of homes and outbuildings, while a second fire crept within a quarter-mile of evacuated homes near Denver.