A wind-driven wildfire near the California-Nevada border grew rapidly to 297 acres on Wednesday, closing westbound Interstate 80 and placing three Nevada County zones under evacuation warnings.

The Floriston Fire began shortly after 10 a.m. near I-80 and Floriston Way, about nine miles northeast of Truckee. Early reports placed the blaze at 10 to 20 acres, but aerial mapping later measured a 295-acre main fire and a separate two-acre spot fire.

As of CAL FIRE’s 12:09 p.m. PDT update on September 16, no containment estimate had been announced. The cause remained under investigation, and officials had not reported any destroyed structures.

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Evacuation warnings expand near Boca Reservoir

Evacuation warnings are in effect for zones NCO-E105, NCO-E106 and NCO-E379. The affected area includes the I-80 corridor and land extending north toward Boca Reservoir, where smoke has affected nearby campgrounds.

An evacuation warning signals a potential threat rather than a mandatory order. Nevada County officials said people requiring additional time, including residents with pets or livestock, should consider leaving immediately.

Residents can check their address and follow changes through the county’s live Genasys evacuation map. Hirschdale, Glenshire and Prosser were close to the affected area but had not been included in evacuation orders in the latest available update.

Westbound I-80 remained closed at the Nevada state line, with no estimated reopening time. Authorities warned motorists to avoid the corridor and expect significant delays. Local reporting indicated additional closures between Floriston and Hinton Road as emergency vehicles moved into the area.

CAL FIRE described the blaze as “wind driven,” moving east along the western side of the highway while producing long-range spot fires. Flames were also climbing steep terrain above the Truckee River Canyon, complicating access for ground crews.

The response included 20 fire engines, five crews, two helicopters, two bulldozers and two water tenders, according to the official CAL FIRE incident report. Air tankers were conducting suppression missions when conditions allowed, while additional engines, crews and heavy equipment were ordered.

CAL FIRE and the Tahoe National Forest are operating under unified command. Fire officials said the flames were threatening the interstate, the Truckee River watershed and surrounding natural resources. Power lines in the Floriston area were also de-energized as a safety measure.

The rapid spread follows other difficult California fire emergencies this year, including the Santa Rosa Island Fire that forced helicopter evacuations and damaged protected land.

Conditions around Floriston could change quickly while winds continue to influence the fire. Residents near the warning zones have been urged to keep essential belongings ready, monitor official alerts and leave early if they need additional evacuation time.