Three wildfires have burned more than 3,500 acres this week in Southern California and triggered evacuation orders and warnings for tens of thousands of residents in Ventura and Riverside counties.
The fires blanketed widespread parts of the region with smoke, lead to an air quality alert through Wednesday evening for parts of of Southern California. Residents in the alert area were advised to avoid or limit outdoor activities due to windblown smoke and ash.
Below, updates on the three major fires burning Wednesday.
Sandy Fire in Simi Valley
The Sandy Fire started Monday in the Ventura County community of Simi Valley northwest of Los Angeles. The fire was at nearly 1,700 acres with containment at 15 percent early Wednesday.
The fire was active overnight, making uphill runs in steep terrain, according to firefighters.
At least one house burned in the early hours of the fire as flames entered a neighborhood at the base of a brush-covered hillside.
Evacuation orders and warnings remained in effect for parts of Simi Valley and nearby communities.
Authorities have not officially determined a cause of the fire, but police said someone using a tractor for brush clearance called to report the machinery struck a rock, possibly producing sparks that started the fire.
The Sandy Fire continues to burn over 1,600 acres in Simi Valley. Michelle Valles reports for the NBC4 News at 6 a.m. on May 20, 2026.
Bain Fire in Jurupa Valley
The Bain Fire started Tuesday north of the Riverside County community of Jurupa Valley. The fire was at nearly 1,400 acres with containment at 25 percent early Wednesday.
Evacuation warnings and orders remain in effect in parts of Jurupa Valley, Riverside and nearby communities.
Details about a cause of the fire were not immediately available.
Firefighters continue to battle the Bain Fire in Jurupa Valley. John Cádiz Klemack reports for the NBC4 News at 6 a.m. on May 20, 2026.
Verona Fire in Homeland
The Verona Fire started Tuesday in the Riverside County community of Homeland. Flames burned 500 acres with containment Wednesday morning at 5 percent.
Evacuation warnings and orders are still in effect for nearby communities.
Details about a cause of the fire were not immediately available.
While firefighters work to determine the cause of the Sandy Fire, police noted that officers received a call from a resident who said he struck a rock while mowing brush with a tractor. Macy Jenkins reports for the NBC4 News at 5:30 p.m. on Tuesday, May 19, 2026.
Wildfire smoke and air quality
The South Coast Air Quality Management District issued the alert, which was in effect until 4:30 p.m. Wednesday, but could be extended depending on developments overnight and early Wednesday. Portions of Ventura, Riverside and San Bernardino counties were under the same order.
In addition to the three fires that started this week, the Santa Rosa Island Fire in Santa Barbara, which broke out Friday and was mapped at 16,942 acres, was also sending smoke into the air over parts of northern Los Angeles County.
The SCAQMD said Orange County and much of LA County were expected to be in the moderate Air Quality Index category or higher, with smoke coming ashore from the Santa Rosa Island Fire. Areas of Los Angeles County adjacent to the Sandy Fire may reach the unhealthy for sensitive groups category or higher.
Depending on fire activity, smoke conditions were expected to improve Wednesday in areas not adjacent to active fires.
Here’s some advice from the SCAQMD.
Limit your exposure by remaining indoors with windows and doors closed or seeking alternate shelter.
Avoid vigorous physical activity.
Run your air conditioning and/or an air purifier. If possible, do not use swamp coolers or whole house fans that bring in outside air.
Avoid burning wood in your fireplace or firepit and minimize sources of indoor air pollution such as candles, incense, pan-frying, and grilling.
If you must be outside, a properly fit N95 or P100 respirator may provide some protection.