California's Park Fire is 25% contained, now the 4th largest in state history

Storms in the forecast this weekend could make efforts to contain the Park Fire in California more difficult, fire officials said Friday.

Wind and lightning from thunderstorm weather could drive erratic fire behavior in what is already challenging terrain full of dense, dry fuels. Temperatures in the region on Friday were also in the triple digits and were forecast to stay hot and dry in the days ahead.

Since July 24, the Park Fire has grown to the fourth largest in California history, officials said. The fire, believed to have started through arson, has burned 624 square miles, or nearly 400,000 acres, and destroyed at least 542 structures. Thousands of firefighters have brought it to 25% containment as of Friday evening.

Portions of Butte, Tehama and Shasta counties remained under evacuation orders on Friday.

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Meanwhile, fires in Colorado have killed one person, damaged or destroyed around 30 structures and triggered evacuation orders for thousands of people on the state's mountainous Front Range. At least one was being investigated as arson.

The largest of the fires there has burned roughly 13 square miles. Officials said responders were making good progress in containing the fires, and may benefit from a brief spell of cooler weather going into the weekend.

Close to 100 other large fires are burning across the U.S. West, including in Washington state, Oregon, Arizona and New Mexico.

The region is in the middle of what is typically considered its fire season, though exact start and end dates for the season are dictated by when the first large fire of the year breaks out and by when the last large fire of the season is controlled. The number, size and duration of large wildfires have all been increasing for decades and are expected to continue to increase under the effects of climate change.