Climate change is a factor but it's not the only one. The long term build up of fuels from 100+ years of fire suppression is in my opinion the biggest problem. More buildings in the WUI are another. But here's a list of ways climate change is making the fire problem worse:
-higher night time temps mean fires don't "lay down" at night like they used to. That was when fire fighters could put in line. Now they often burn stronger at night, which is totally nuts.
-reduced summer rainfall in the sierras is making fuel moisture lower, making fires burn hotter and more readily.
-higher winter temps have allowed the spread of bark beetles. Some places in the sierras have 90% beetle kill. That sure wasn't the case
when I was looking at trees there for the USFS in the '80s
-this summer's dry lightning storm that caused so many fires on the west coast wasn't normal. I don't know if it was caused by climate change but we have been getting more carryover from big storms to the south than we usually get.