(CNN) Another round of heavy rain was hitting California on Wednesday, putting millions of people under a flash-flood watch and spurring precautionary evacuations in several wildfire-scarred areas vulnerable to mudflows .

Series of winter storms to usher in the coldest air of the season In what should be the strongest in a series of recent storms, up to 3 inches of rain are expected in Southern California through Thursday and 6 inches could fall in central portions of the state. The heavy rain was expected to roll in Wednesday evening. The rain could lead to mudflows and flooding in areas burned by wildfires last year. Nearly 15 million people were under a flash-flood watch Wednesday morning from the Los Angeles area to central and northern parts of the state, the National Weather Service said. A woman carries an umbrella while crossing a street in San Francisco on Tuesday. Evacuations and closures Read More Among the wildfire-scarred areas watching particularly closely for mudflows: • Los Angeles County : Evacuations have been ordered for several communities with steep slopes deemed at risk for mudslides, especially after last year's Woolsey Fire scorched the area. Evacuation centers have been opened in Santa Monica and Agoura . Schools in the seaside town of Malibu, which was hit by last year's fires, were closed Wednesday as a precaution. "You can't outrun or fight these mudslides," Malibu Mayor Jefferson Wagner said in a video message Tuesday urging people to follow evacuation orders. "Stay cautious, stay dry, and let's get through this next event without issue." Rainfall is expected to increase by noon Wednesday in Southern California "and become heavier in the evening and overnight," the National Weather Service said . • Ventura County : Mandatory evacuations were issued Tuesday for parts of this county west of Los Angeles, including its south coast and the Matilija and Wheeler Springs areas. Parts of the county were scorched by the Woolsey, Hill and Thomas fires. "(The rain) may cause significant debris flows and flooding in the recent burn areas," the county's emergency information website reads. "In addition, some rockslides can be expected along canyon roadways outside the burn areas." • Butte County : The sheriff's office in this Northern California county urged evacuations in the town of Pulga, about a 100-mile drive north of Sacramento, from Tuesday night into Thursday morning. "If flooding occurs, this can quickly become a dangerous and life-threatening situation," the sheriff's office said. Parts of the county were burned last fall by the Camp Fire, the state's most deadly and destructive wildfire on record. Photos: In pictures: Wildfires tear across California Jacob Saylors, 11, walks through the burned remains of his home in Paradise, California, on Sunday, November 18. His family lost a home in the same spot to a fire 10 years earlier. Hide Caption 1 of 102 Photos: In pictures: Wildfires tear across California Lidia Steineman, who lost her home in the Camp Fire, prays during a vigil for fire victims on November 18 in Chico, California. More than 50 people gathered at the memorial service. Hide Caption 2 of 102 Photos: In pictures: Wildfires tear across California From left, California Gov.-elect Gavin Newsom, California Gov. Jerry Brown, President Donald Trump, Paradise Mayor Jody Jones and FEMA Administrator Brock Long survey damage left by the Camp Fire in Paradise, California, on Saturday, November 17. The death toll from the Camp Fire has risen to 76 and more than 1,200 people remain unaccounted for. Hide Caption 3 of 102 Photos: In pictures: Wildfires tear across California A child wears a smoke mask while watching President Trump''s motorcade in Chico on November 17. Hide Caption 4 of 102 Photos: In pictures: Wildfires tear across California Fire evacuees sift through donated items in a Chico parking lot November 17. Hide Caption 5 of 102 Photos: In pictures: Wildfires tear across California A group of children hold an American flag as the motorcade of President Donald Trump drives through Chico, California, on November 17. Hide Caption 6 of 102 Photos: In pictures: Wildfires tear across California A firefighter searches for human remains on Friday, November 16, in a Paradise trailer park destroyed in the Camp Fire. Hide Caption 7 of 102 Photos: In pictures: Wildfires tear across California President Donald Trump visits a neighborhood impacted by the Woolsey Fire in Malibu, California, on November 17. Hide Caption 8 of 102 Photos: In pictures: Wildfires tear across California Dakota Keltner, right, rests on Havyn Cargill-Morris on November 16 in a truck at a makeshift encampment outside a Walmart store in Chico, California. The camp became a temporary respite for people displaced by the Camp Fire. Hide Caption 9 of 102 Photos: In pictures: Wildfires tear across California A burned neighborhood is seen on Thursday, November 15, in Paradise, California. Hide Caption 10 of 102 Photos: In pictures: Wildfires tear across California Rescue workers sift through rubble in search of human remains on Wednesday, November 14, at a burned property in Paradise. Hide Caption 11 of 102 Photos: In pictures: Wildfires tear across California Firefighters work to control the Camp Fire on November 14 north of Oroville, California. Hide Caption 12 of 102 Photos: In pictures: Wildfires tear across California Evacuee Denise Chester hugs her son, Antonio Batres, as she volunteers her time sorting clothes on November 14 at a makeshift shelter in Chico. Chester, who didn't want to know yet whether her home survived, said: "I want to help. I don't want to shut down." Hide Caption 13 of 102 Photos: In pictures: Wildfires tear across California Tape outlines the location where sheriff's deputies on November 14 recovered the body of a Camp Fire victim. Hide Caption 14 of 102 Photos: In pictures: Wildfires tear across California Magalia resident Luis Badres and his family left his home because of the Camp Fire. They were living in a tent on Tuesday, November 13, in the parking lot of a Chico Walmart. Hide Caption 15 of 102 Photos: In pictures: Wildfires tear across California A long line of residents seeking to return to Malibu wait at a checkpoint on November 13 on Pacific Coast Highway after Woolsey Fire evacuation orders were lifted for the eastern portion of the city. Hide Caption 16 of 102 Photos: In pictures: Wildfires tear across California A helicopter flies near the Woolsey Fire burning in the Santa Monica Mountains National Recreation Area. Hide Caption 17 of 102 Photos: In pictures: Wildfires tear across California Roger Kelton wipes away tears on November 13 while searching through the remains of his mother-in-law's home in Agoura Hills. It was destroyed by the Woolsey Fire. Hide Caption 18 of 102 Photos: In pictures: Wildfires tear across California A melted fence runs along a hillside as firefighters battle the Woolsey Fire in Agoura Hills on November 13. Hide Caption 19 of 102 Photos: In pictures: Wildfires tear across California Firefighters search through the remains of a Paradise house on November 13. Hide Caption 20 of 102 Photos: In pictures: Wildfires tear across California Smoke fills the horizon on November 13 as an airplane flies near a flare-up of the Woolsey Fire near Lake Sherwood. Hide Caption 21 of 102 Photos: In pictures: Wildfires tear across California A fire truck drives through part of Paradise on November 13. Hide Caption 22 of 102 Photos: In pictures: Wildfires tear across California An air tanker drops water on a fire along the Ronald Reagan Freeway in Simi Valley on Monday, November 12. Hide Caption 23 of 102 Photos: In pictures: Wildfires tear across California Samantha Esau and Emily Garcia take in stray cats from an evacuated Paradise home on November 12. Hide Caption 24 of 102 Photos: In pictures: Wildfires tear across California Firefighters put out hot spots in Paradise on November 12. Hide Caption 25 of 102 Photos: In pictures: Wildfires tear across California Joseph Grado and his wife, Susan, embrace at a shelter in Chico on November 12. The Camp Fire destroyed their home. Hide Caption 26 of 102 Photos: In pictures: Wildfires tear across California A firefighter battles a fire in Simi Valley on November 12. Hide Caption 27 of 102 Photos: In pictures: Wildfires tear across California A plane drops fire retardant on the Woolsey Fire near Malibu on November 12. Hide Caption 28 of 102 Photos: In pictures: Wildfires tear across California Betsy Ann Cowley walks through Pulga, near where investigators were trying to determine the cause of the Camp Fire. Hide Caption 29 of 102 Photos: In pictures: Wildfires tear across California A resident sprays down a roof as firefighters battle the Peak Fire in Simi Valley. Hide Caption 30 of 102 Photos: In pictures: Wildfires tear across California Shawn Slack carries a chainsaw on November 12 after trees burned in Paradise. Hide Caption 31 of 102 Photos: In pictures: Wildfires tear across California Chris and Nancy Brown embrace while looking over the remains of their home on November 12. Hide Caption 32 of 102 Photos: In pictures: Wildfires tear across California Firefighters put out hot spots in Thousand Oaks on November 12. Hide Caption 33 of 102 Photos: In pictures: Wildfires tear across California Firefighters battle a fire in Simi Valley on November 12. Hide Caption 34 of 102 Photos: In pictures: Wildfires tear across California A ferry makes its way toward Alcatraz Island on November 12 as the San Francisco skyline is obscured by smoke that drifted over from the Camp Fire. Hide Caption 35 of 102 Photos: In pictures: Wildfires tear across California A vehicle drives through smoke near Pulga on Sunday, November 11. Hide Caption 36 of 102 Photos: In pictures: Wildfires tear across California Firefighters battle the Woolsey Fire in Malibu on November 11. Hide Caption 37 of 102 Photos: In pictures: Wildfires tear across California A helicopter drops water while battling the Camp Fire near Pulga on November 11. Hide Caption 38 of 102 Photos: In pictures: Wildfires tear across California Firefighters work at the Salvation Army Camp in Malibu on Saturday, November 10. Hide Caption 39 of 102 Photos: In pictures: Wildfires tear across California A bag containing human remains lies on the ground on November 11 as officials continue to search for victims at a burned-out home in Paradise. Hide Caption 40 of 102 Photos: In pictures: Wildfires tear across California Cathy Fallon, who stayed behind in Paradise to tend to her horses during the Camp Fire, embraces Shawna De Long, left, and April Smith, right, who brought supplies for the horses. Hide Caption 41 of 102 Photos: In pictures: Wildfires tear across California Firefighters douse embers off a canyon road that cuts across the mountains to Malibu. Hide Caption 42 of 102 Photos: In pictures: Wildfires tear across California A plane drops fire retardant on a burning hillside in Malibu on November 11. Hide Caption 43 of 102 Photos: In pictures: Wildfires tear across California Evacuee Brian Etter and his dog Tone, who escaped the Camp Fire on foot, rest in the parking lot of a Chico church on November 11. Hide Caption 44 of 102 Photos: In pictures: Wildfires tear across California Culver City firefighters watch the Woolsey Fire from a burned home in Los Angeles. Hide Caption 45 of 102 Photos: In pictures: Wildfires tear across California The remains of a Los Angeles home destroyed by the Woolsey Fire are seen on November 11. Hide Caption 46 of 102 Photos: In pictures: Wildfires tear across California The sun rises over the Pacific Ocean on November 11 as the Woolsey Fire burns in Malibu. Hide Caption 47 of 102 Photos: In pictures: Wildfires tear across California Firefighters battle a blaze in Malibu on Saturday, November 10. Hide Caption 48 of 102 Photos: In pictures: Wildfires tear across California A woman runs in Calabasas as firefighters work to control a flare-up from the Woolsey Fire on November 10. Hide Caption 49 of 102 Photos: In pictures: Wildfires tear across California The Camp Fire burns November 10 in the hills near Big Bend. Hide Caption 50 of 102 Photos: In pictures: Wildfires tear across California Sheriff's deputies carry a body bag with a Camp Fire victim on November 10. Hide Caption 51 of 102 Photos: In pictures: Wildfires tear across California Scorched hillsides and damaged power lines are seen on November 10 along the Pacific Coast Highway in Malibu. Hide Caption 52 of 102 Photos: In pictures: Wildfires tear across California Araya Cipollini cries November 10 near the remains of her family's home in Paradise. Hide Caption 53 of 102 Photos: In pictures: Wildfires tear across California Los Angeles County firefighters work in Malibu Creek State Park on November 10. Hide Caption 54 of 102 Photos: In pictures: Wildfires tear across California A deer looks on from a burned residence in Paradise on November 10. Hide Caption 55 of 102 Photos: In pictures: Wildfires tear across California A fire truck is seen on the Pacific Coast Highway as the Woolsey Fire burns in Malibu on November 10. Hide Caption 56 of 102 Photos: In pictures: Wildfires tear across California Eric England searches through a friend's vehicle in Paradise on November 10. Hide Caption 57 of 102 Photos: In pictures: Wildfires tear across California Sheriff's deputies walk November 10 through a neighborhood destroyed by the Camp Fire. Hide Caption 58 of 102 Photos: In pictures: Wildfires tear across California A satellite image from November 10 shows vegetation that was burned as a result of the Woolsey Fire. Hide Caption 59 of 102 Photos: In pictures: Wildfires tear across California Firefighters meet in Paradise on November 10. Hide Caption 60 of 102 Photos: In pictures: Wildfires tear across California Roger Bloxberg and his wife, Anne, hug on Friday, November 9, as they watch a wildfire on a Los Angeles hilltop. Hide Caption 61 of 102 Photos: In pictures: Wildfires tear across California Malibu Mayor Rick Mullen, who is also a firefighter, surveys a house engulfed in flames on Friday, November 9. Hide Caption 62 of 102 Photos: In pictures: Wildfires tear across California A massive smoke plume, powered by strong winds, rises above the Woolsey Fire in Malibu on November 9. Hide Caption 63 of 102 Photos: In pictures: Wildfires tear across California Cathy Fallon stands near the charred remains of her Paradise home on November 9. The Camp Fire has wiped out much of the town north of Sacramento. Hide Caption 64 of 102 Photos: In pictures: Wildfires tear across California A firefighter sprays down palm trees as the Woolsey Fire burns in Malibu on November 9. Hide Caption 65 of 102 Photos: In pictures: Wildfires tear across California Llamas are tied to a lifeguard stand on a Malibu beach on November 9. Hide Caption 66 of 102 Photos: In pictures: Wildfires tear across California Smoke is seen over the Pacific in this photo taken from a helicopter over Malibu on November 9. Hide Caption 67 of 102 Photos: In pictures: Wildfires tear across California A woman in Malibu reacts to devastation on November 9. Hide Caption 68 of 102 Photos: In pictures: Wildfires tear across California A row of palm trees stands as the Woolsey Fire continues to burn in Malibu on November 9. Hide Caption 69 of 102 Photos: In pictures: Wildfires tear across California From left, firefighters Cory Darrigo, Omar Velasquez and Sam Quan rest in a Westlake Village backyard after battling the Woolsey Fire all night. Hide Caption 70 of 102 Photos: In pictures: Wildfires tear across California Gabi and Jonah Frank walk on the Pacific Coast Highway as the Woolsey Fire threatens their Malibu home on November 9. Hide Caption 71 of 102 Photos: In pictures: Wildfires tear across California A satellite image taken by NASA's Operational Land Imager shows the Camp Fire in Northern California. Hide Caption 72 of 102 Photos: In pictures: Wildfires tear across California A firefighter keeps watch as the Woolsey Fire burns a home near Malibu Lake on November 9. Hide Caption 73 of 102 Photos: In pictures: Wildfires tear across California The Woolsey Fire burns in Malibu on November 9. The community is known for celebrity beachside homes. Hide Caption 74 of 102 Photos: In pictures: Wildfires tear across California Doug Thomas and his dog Hanna rest November 9 while they await word if they can return to their Malibu Lake home. Hide Caption 75 of 102 Photos: In pictures: Wildfires tear across California Cars destroyed by the Camp Fire sit in a used-car lot in Paradise on November 9. Hide Caption 76 of 102 Photos: In pictures: Wildfires tear across California Firefighters battle flames in Thousand Oaks early on November 9. Hide Caption 77 of 102 Photos: In pictures: Wildfires tear across California Evacuees rest on cots supplied by the Red Cross at a Los Angeles high-school gym on November 9. Hide Caption 78 of 102 Photos: In pictures: Wildfires tear across California Fire Capt. Steve Millosovich, battling the Camp Fire in Big Bend, carries a cage of cats that fell from an evacuee's pickup. Hide Caption 79 of 102 Photos: In pictures: Wildfires tear across California Smoke billows above Malibu trees in this photo posted to Instagram by Julie Ellerton. Hide Caption 80 of 102 Photos: In pictures: Wildfires tear across California Firefighters push a vehicle from a garage as the Woolsey Fire burns a home in Malibu on November 9. Hide Caption 81 of 102 Photos: In pictures: Wildfires tear across California Patients are evacuated from Paradise's Feather River Hospital as it burns on Thursday, November 8. Hide Caption 82 of 102 Photos: In pictures: Wildfires tear across California Juanita and Wayne McLish sit on a curb November 8 after losing their house to the Camp Fire in Paradise. Hide Caption 83 of 102 Photos: In pictures: Wildfires tear across California The Hill Fire burns in Thousand Oaks on November 8. Hide Caption 84 of 102 Photos: In pictures: Wildfires tear across California The Woolsey Fire burns in Ventura County, where Jason Bauer told CNN his parents had just been evacuated from their home. Hide Caption 85 of 102 Photos: In pictures: Wildfires tear across California People embrace in the parking lot of a Paradise hospital as the Camp Fire engulfed it on November 8. Hide Caption 86 of 102 Photos: In pictures: Wildfires tear across California The Paradise Inn burns on November 8. Hide Caption 87 of 102 Photos: In pictures: Wildfires tear across California A firefighter works to extinguish a spot fire at a home in Paradise. Hide Caption 88 of 102 Photos: In pictures: Wildfires tear across California Vehicles and homes burn as the Camp Fire rips through Paradise on November 8. Hide Caption 89 of 102 Photos: In pictures: Wildfires tear across California Dogs roam a burned-out neighborhood in Paradise. Hide Caption 90 of 102 Photos: In pictures: Wildfires tear across California Hospital staff and first responders evacuate the Feather River Hospital in Paradise on November 8. Hide Caption 91 of 102 Photos: In pictures: Wildfires tear across California A fire emergency crew works to protect the Paradise Town Hall from the encroaching Camp Fire on November 8. Hide Caption 92 of 102 Photos: In pictures: Wildfires tear across California A home burns as the Camp Fire rages through Paradise. Hide Caption 93 of 102 Photos: In pictures: Wildfires tear across California A vintage car rests among debris in Paradise. Hide Caption 94 of 102 Photos: In pictures: Wildfires tear across California Medical personnel move patients as the Feather River Hospital is evacuated in Paradise on November 8. Hide Caption 95 of 102 Photos: In pictures: Wildfires tear across California Smoke fills the sky over Paradise on November 8. Paradise, located about 85 miles north of Sacramento, has 26,000 residents. Hide Caption 96 of 102 Photos: In pictures: Wildfires tear across California The remains of a building are seen after being consumed by the Camp Fire. Hide Caption 97 of 102 Photos: In pictures: Wildfires tear across California A firefighter monitors a burning home on November 8. Hide Caption 98 of 102 Photos: In pictures: Wildfires tear across California California Highway Patrol officers attempt to transfer a potbelly pig they rescued in Butte County on November 8. Hide Caption 99 of 102 Photos: In pictures: Wildfires tear across California A Paradise home is engulfed in flames on November 8. Hide Caption 100 of 102 Photos: In pictures: Wildfires tear across California Firefighters monitor a back fire while attempting to save homes in Paradise on November 8. Hide Caption 101 of 102 Photos: In pictures: Wildfires tear across California Flames burn inside a van as the Camp Fire tears through Paradise on November 8. Hide Caption 102 of 102 Strong winds and heavy snow, too Wednesday's storms also are expected to bring strong winds to central and northern parts of California, including San Francisco. Wind gusts could reach around 60 mph. The storms also will bring snow -- up to 6 feet -- to parts of the Sierra Nevada. A blizzard warning is in effect into Thursday morning for elevations above 6,500 feet.