California Gov. Jerry Brown (D) blamed climate change for the wildfires that are burning in at least nine locations across the southern part of the state.

The worst of the fires have been concentrated in north San Diego County. Evacuation orders for thousands of residents in Carlsbad and San Marcos were lifted late Thursday.

“The heat is terrible. The last few years have been the driest in recorded California history. They think they’ve got this thing contained or about to,” Brown told CNN. “But they’ve got fires all over the place, and most serious of all, California now is a fire season that’s 70 days longer. So it’s getting longer. And the most serious fires have occurred in the last decade. And so things are getting worse.”

“And despite what you may hear in Washington, climate change is a factor here. We’ve got to live with this. It’s not about theory. It’s not about politics. This is about fires on the ground, people’s homes, firefighters. We’re dealing, we’re adapting, and it’s quite a challenge, let me tell you.”

When asked about human involvement in the spread of the fires and not just Mother Nature, Brown said “any fire is caused by wind, by the fuel that happens to be there, by how dry the timber and the grass is, whether there’s any moisture or not.”

“Right now there’s almost none and, yes, those conditions are definitely caused by climate change, global warming induced by human activity, by the 7 billion people that are generating all this stuff,” he continued. “So we’ve got to make changes. But right now in California, we are dealing with, as we are talking now with the consequences, and we’re handling it the best way we can.”

Two teens were arrested Thursday for starting two brush fires near Escondido, heightening suspicion that arson was involved in the county’s biggest blazes.

“I don’t know that directly, but I do know that people do stupid things,” Brown said. “They throw a cigarette butt out of a car, or they’re doing a little fire somewhere and a spark gets away. They don’t realize that an ember in these dry conditions, it’s all fuel. It’s all kindling because of the dry conditions, and they are very dry. So if someone really wants to intentionally create fires, it’s a pretty — unfortunately and tragically, it’s a very easy task.”

“I tell you right now, it’s hot. I was in San Diego just two days ago. It was plenty hot. Like 100 degrees, something that I’ve never seen. The humidity is below 10 percent. There’s a wind anywhere 8 to 15 miles an hour, depending upon the time of the day. I mean, these are perfect conditions for conflagrations and fires all over the place. So we just hope and pray that a little more cold weather comes along, and we have the equipment.”