At home on Atlas Peak Road, on a hillside overlooking the Napa Valley, he noticed the breeze rising all evening after a beautiful October day.
"It started picking up to the point where as we got into bed, branches were falling on the roof and making a racket," Harberts says.
An hour or so later, for no reason he can explain, Harberts climbed out of bed to take a look outside.
"I didn’t hear anything, I didn’t see anything," he says. "I just got up. I walked to the front of our bedroom, and I looked out over the valley, and there was a wall of fire that was coming."
Harberts says one thought leapt to mind: "That I better be making very good decisions because this is a critical situation." He called to his wife, Peggy, " 'Honey, get up, we have got to get out now.’ "
Harberts had to make sure other people got out, too, including two tenants on the property and his 97-year-old mother and her caregiver.
And one other family member: his son’s dog, a black Labrador retriever named Drake.
But by the time Harberts and his family were moving, there was no way to get off of Atlas Peak Road -- a steep, winding, narrow ribbon of asphalt with just one way in and out.
Harberts knew the fire was climbing the slope from the valley, so he tried to drive uphill. But he immediately encountered neighbors who said the fire was blocking the road in that direction.
For an anxious hour or so, Harberts and his family wondered whether help would come.
Then, a man in a California Highway Patrol flight suit appeared, seemingly out of nowhere.
"And I got out of my car," Harberts says. "I ran up to him and said, ‘I’ve got a 97-year-old mother. Do you have a plan? We gotta get out of here.' "
The man was part of a two-person CHP helicopter crew that had landed to try to rescue people trapped by the advancing flames.
"He said, 'You know, right up the street there, right up the road, there is a field, and we have a helicopter and we can get you out.' "
But the chopper was already full when Harberts arrived with his family. After another wait, the helicopter crew returned for more evacuees.
"He said, ‘You guys get in,’ " Harberts recalls. "So there was four of us: my mom, her caregiver, my wife. And when we had loaded them up I said, ‘I’ve got my dog.’ I told the pilot we’ve got our dog. And he said, ‘No dogs.’ "
So, Drake, the black Lab, was left behind in a pickup truck. The next morning, a family friend made it through police lines -- and found the truck intact and the dog waiting.
"He looked in the window, and there's Drake, saying, 'Why did you leave me?' " Harberts says. "And he was perfectly fine. Perfectly fine."
He owns and runs Bubbling Well Pet Memorial Park -- yes, a pet cemetery.
If you're a documentary film fanatic, the name might be familiar. That's because Bubbling Well was featured in the widely celebrated “Gates of Heaven,” the first feature by filmmaker Errol Morris, released 40 years ago this year.
The movie captures Bubbling Well and the Harberts family in the park's early years. The cemetery was created by Dan's father, the late John Calvin Harberts, an entrepreneur who thought he detected a new need in a society that was placing a new importance on four-legged family members.
Dan Harberts says he was a student at Chico State in the early 1970s when he got a phone call from his father.
"And he said, 'Son, I've got an idea. We're going to start a pet cemetery up on the hill.' And I said, 'Dad, I don't think that's the greatest idea in the world.' But he was a visionary."
Morris' documentary took its title from a Cal Harberts soliloquy near the end of the film in which he explains his project's spiritual dimension.
"God is supposed to know when the sparrow falls, when the lilies of the field bloom," the elder Harberts told Morris. "So surely, at the gates of heaven, an all-compassionate god ... is surely not going to say, 'Well, you're walking in on two legs, you can go in; you're walking in on four legs, we can't take you."
Even immediately after the Atlas Peak fire, the pet cemetery’s well-watered landscaping was verdant and looked largely untouched.
But as Dan Harberts pointed out on a recent tour of the grounds, whatever could burn at Bubbling Well, did. The cemetery's business office, chapel and workshop were all destroyed. So was Harberts' home, along with two other residences on the property.
But the cemetery, which works with more than three hundred veterinarians and clinics in Northern California to handle recently deceased dogs, cats and other pets, has continued to operate from a temporary office several miles away in Napa.
"We have a lot of pet owners who have pre-need arrangements where they have burial sites that they've already purchased," Harberts says. "We have people who want to bury their pets here, so we're having to drive back and forth to do the business up here."
Rebuilding has been slow. Harberts says preliminary work like grading the property for construction probably won't begin until the end of the summer.
Much of the fire debris has been hauled away. But the areas around the park's entrance and home sites are raw, still marked by blackened foundations and charred trees.
"I’m sure once we start grading and start actually having activity -- I know I’m going to feel a lot better when I start seeing things happen," he says. "But to see it in this state, it’s really a kind of depressing thing for me."
But Harberts also says he’s looking ahead. He says he expects the business to continue to grow and that his son David, 29, plans to take over some day.
"We are third generation. Our location is premier; there is nothing like it in the United States," Harberts says. "I fully expected to keep on keeping on."