Mostly, a change in the weather. To assume forest management can control the current fire problem is folly.
Forests are being managed by Mother Nature, in the long term. Her management schedule does not fit the 90 day management expectations of humans who believe they are in control
Recommend going back and reading Post 39 by grundle, including the article at the link.
"On the left side, the earth is black as tar, and scorch marks as tall as a person scar the trunks of the mature oak trees scattered throughout the field. But on the right side, the ground is tan and brown, and you have to look hard at the still-green oaks to see any evidence of the fire that raged through here just a few weeks before. It’s no mystery to Berleman why the fire behaved so differently on the two sides of the trail... When flames hit the field on the left of the path, they met a dense wall of thigh-high grass that hadn’t been mowed, grazed or burned for 20 years. The flames must have been 5 or 6 feet tall. On the right side, however, Berleman had set a prescribed burn just this spring. So when the October wildfire hit, patches of fire blazed, but with so little fuel, the flames remained only inches high."
Most out of control forest fires are due to bad forest fire management. We used to let loggers do that for us, as they chopped down trees. They would also clear out the overgrowth at the same time.
However since we put the kibosh on logging, we didn’t take up the slack by maintaining the forests. This has resulted in a lot of over growth in the forest, which has made them susceptible to forest fires when the conditions start them.
We can’t stop forest fires, but we can have a lot of effect on how serious they get by proper forestry management.
Real / actual Foresters and Forest Managers do NOT have “90 day management expectations”. At least not 99% of the time, anyway.
(The other 1% is usually stuff like: “Clean out the worst of the dead branches and trees 1st, before some hiker [etc.] gets clonked by a big piece of deadwood coming down”.)
My Dad taught proper Forest Management for over 50 years. and proper Forest Management applied over a period of years most certainly can minimize and reduce fire risks and damages, even in droughts.