All that rain, and now all that brush on fire in Southern California. What gives?

After a winter during which Los Angeles received more rain than notoriously drippy Seattle, anyone who had only recently packed away their foul-weather gear might have believed the worst of the year-round brush fire season in Southern California would be delayed.

When firefighting officials assembled in Irvine in May to warn the public that the threat was coming soon, a lush green hillside stood as a backdrop.

And yet on June 15, the Post fire ignited in Gorman, north of Los Angeles, and it has burned and burned and burned some more, blackening more than 15,000 acres as of Tuesday, June 18. Not since the Elm fire in Fresno County started on May 18, 2017, has the state firefighting agency, Cal Fire, responded earlier in the year to a blaze that would ultimately burn 10,000 acres or more. (The U.S. Forest Service lists only fires on federal lands that burned at least 40,000 acres.)

Additionally, the Hesperia fire had burned 1,078 acres and the Lisa fire east of Moreno Valley had burned 867 acres as of Tuesday.

How could so much burn so soon after a wet winter?

“That false sense of security that the ground must be moist because of the rain is not true,” said Kenichi Haskett, a spokesman for the commanders of the Post fire.

Eric Sherwin, a spokesman for the San Bernardino County Fire Department, said drought-like conditions the past several years limited the growth of high grasses, which are the first vegetation to dry out during the transition from spring into summer. The denser growth beneath the grasses retains moisture longer.

“We’ve had two very nice rainy seasons that have allowed a very robust grass crop to develop,” Sherwin said. “Grass fires burn incredibly quickly … because it’s a (thin) fuel, and it’s easy to preheat the fuel ahead of the fire. So it is not unusual to see a fire burn through a grass crop of 1,000 acres in the first few hours.”

Sherwin said he has viewed recordings of firefighters in Gorman running with their hoses alongside the wind-driven flames in a futile attempt to extinguish them.

“They can’t move fast enough,” Sherwin said.

The brush below the grasses, thick and dense from years of not having burned, will soon dry in the consistent summer heat, said Capt. Sean Doran, a spokesman for the Orange County Fire Authority.

“They are hiding in the midst of the grasses we see while driving down the road,” Doran said.

OCFA officials, at the May news conference, urged the public not to let their guard down because of the sight of lush hillsides. Wind will dry out the remaining brush.

OCFA, on top of urging the clearance of 100 feet of defensible space, is focused on a second message: Making sure that no combustible materials are placed within 5 feet of homes. That includes firewood, furniture, recreational vehicles, bark and mulch and dying plants, Doran said.

“We could have a hot, dry day anytime, so rather than predict when the fire will happen, we can control what we can control, and that is home hardening,” Doran said. “Wildfires are woven into our history in Southern California and Orange County, so this is who we are.”

The website Readyforwildfire.org has been updated with a checklist for evacuation preparations, lists of fire-resistant plants that can be placed around the home and other safety information, said Chloe Castillo, a spokeswoman for Cal Fire’s San Bernardino Unit.

Sherwin urged residents to prevent fires so they don’t have to defend their homes against one. The San Bernardino National Forest,, he said, has more homes — 40,000 — than any other national forest.

Some fires are started when well-meaning residents mow brush during the warmest times of the day, around 1 p.m. to 5 p.m. Better to do the work early in the day, Sherwin said, when the brush is more moist. Accidental fires, Sherwin noted, have the same destructive force as blazes that are maliciously set.

“Be smart in your activities,” Sherwin said.