Nearly 1,500 firefighters have made slow progress on the Helena Fire in Trinity County, which destroyed 72 homes over a week’s time.
On Wednesday evening, Cal Fire said the blaze that has charred 15,880 acres was 30 percent contained, up from 14 percent the day before.
The Helena fire erupted Aug. 30 west of Weaverville along Highway 299 in isolated, forested northwestern California.
The Helena Fire is close to merging with the Fork Fire, which is burning in the Trinity Alps Wilderness. The Fork Fire has burned 3,160 with no containment as of Wednesday evening. Fire officials expect the two fires to burn together in the coming days.
The highest priority for the Helena Fire is to keep the fire north of Junction City and from spreading east toward Weaverville, according to fire officials.
Cal Fire noted that high temperatures and rough terrain have challenged firefighters on the lines for days. A low-pressure system was expected to move through Northern California on Wednesday night and Thursday, increasing the chance of showers and thunderstorms, as well as cooler temperatures and higher humidity.
About 9:30 a.m. Wednesday, the National Weather Service issued a Red Flag Warning for large portions of Northern California, noting the possibility of thunderstorms and lightning through Thursday evening.
NWS warnings alert fire departments of the possibility of weather that could create fires or affect firefighting efforts. A Red Flag Warning is the considered the highest level of alert.
Officials urge extreme caution because a simple spark can cause a major wildfire. Lightning strikes also are capable of setting off major blazes, which can be pushed along by high winds.
In Butte County, Cal Fire said the Ponderosa Fire, which has burned more than 4,000 acres, was 93 percent contained as of Wednesday evening. That fire torched 32 residences since it started Aug. 29 at Ponderosa Way and Lumpkin Road, east of Lake Oroville.