Firefighters in Southern California have made some hard-won progress against the huge infernos, but lost ground on the largest fire over the weekend.

The Thomas Fire regained strength and surged on Sunday to burn more than 230,500 acres, up from 143,000 acres on Friday. It spread from Ventura County into Santa Barbara County and is now the fifth-largest wildfire in modern California history with only 15 percent containment.

And it’s just one of the five major fires still spreading as of Monday, according to the California Department of Forestry and Fire Protection. They’ve all gotten a boost from the Santa Ana winds, the late fall dry winds that have been unusually stiff this year.

Health officials are growing increasingly worried about dangerous air quality as ash and soot fill the skies. Some areas have already reported record air pollution in the wake of these infernos.

The total torched area from fires this month now tops 256,000 acres, or 400 square miles, a third larger than the area of New York City. The fires have scorched hillsides, destroyed dozens of properties, and shrouded highways in smoke in the state’s worst fire season on record.

Here is the smoke dispersion forecast for Friday. Smoke could impact coastal sections of Orange and San Diego County on Friday. #cawx pic.twitter.com/yajEkeVthI — NWS San Diego (@NWSSanDiego) December 8, 2017

Gov. Jerry Brown declared a state of emergency last week and President Trump followed suit on Thursday as the fires continue to burn through one of the most populated parts of the county.

Los Angeles County has more than 10 million residents, 3.3 million live in San Diego County, Riverside County has 2.1 million denizens, 440,00 are in Santa Barbara County, and Ventura County is home to 850,000.

The National Weather Service warned last week that winds could get as high as 80 mph — in the range of a Category 1 hurricane — which was the first time the agency has activated the purple level threat warning in the state.

The fires have already forced more than 200,000 people from across the region to flee as embers skipped across highways, making a hellish commute for Angelenos.

Not the typical morning commute... pic.twitter.com/kJIOQeqsIK — A. Mutzabaugh CMT (@WLV_investor) December 6, 2017

Hundreds of schools in the region closed down because of the flames, and the University of California Los Angeles canceled classes last week.

The Creek Fire near Sylmar burned more than 15,600 acres since it ignited Tuesday, triggering evacuation orders affecting more than 120,000 people. Officials report the blaze is 95 percent contained now.

Meanwhile, the biggest fire, the Thomas Fire in Ventura County, has forced 27,000 people to flee after destroying or damaging more than 600 structures and threatening 15,00 buildings. Officials report the fire is only 15 percent contained as of Monday morning.

Trouble in Paradise: The #ThomasFire looming over Ventura as seen from #SantaBarbara this evening. Dangerous #SantaAna winds this week. #Ventura #SantaPaula #WildFire A post shared by Sundance Beach (@sundancebeach) on Dec 5, 2017 at 3:57am PST

Farther north, 1,200 homes were evacuated as the Rye Fire torched 6,000 acres. It is now 93 percent contained.

WOW! Check out this picture of the #RyeFire burning in Valencia near Magic Mountain. (Photo courtesy: Dustin Bright) pic.twitter.com/dzNL5NAc8S — 23ABC News (@23ABCNews) December 5, 2017

Flames from the Skirball Fire swiftly consumed 422 acres near Sepulveda Pass Wednesday morning, shutting down the 405 Freeway and threatening multimillion-dollar homes in Bel Air. The Los Angeles Fire Department reports that the blaze is 85 percent contained.

Firefighters also contained the Liberty Fire in Riverside County after it spread over 300 acres since igniting Thursday afternoon.

One of the newer fires, the Lilac Fire in San Diego County, burned 4,100 acres since igniting Thursday morning, but is now 80 percent contained.

A heartbreaking sight. The fast-moving #LilacFire ripped through structures in #Bonsall, burning homes in the San Luis Rey Mobile Home Park. #NBC7 A post shared by NBC 7 San Diego (@nbcsandiego) on Dec 7, 2017 at 5:13pm PST

This devastation has been years in the making, as Californians have kept building homes in high-risk areas. Meanwhile, record heat this summer following a wet winter left much of the state buried in dry kindling.

Last month, tens of thousands of Californians fled flames and smoke from the deadly record wine country fires in the northern part of the state. The United States as a whole has suffered the second-worst fire season on record, with more than 9.1 million acres burned this year so far.