For some, post-fire living will not be much different. I drove through the area last weekend and some spots look no different, yet when you round a corner in the road a 1/4 mile away, you find massive black hillsides. I'm sure values will suffer some due to the less attractive views from some parcels.
Insurance carriers are being cautious about writing in the area and some have stopped. Check with your insurance carrier before proceeding. Closings have been delayed while lenders confirm that no damage was done to an individual property. I was hired by a lender to confirm that over 30 properties for which they old the mortgage were un-damaged in the fire. I had one vacant parcel of land listed for an out of state seller, and that property was completely burned. It has been taken off the market because we estimate that the property is no longer worth even what the owner owes.
There have been mudslides with the rains that came after the fires. In the news stories I have read, the professionals expect to have more of these in coming years until the vegetation takes hold again. I would certainly look upstream or up the mountain above any property in which you are interested, prior to purchasing.
I would expect that the properties that were not affected, nor suffered negative effects of view loss or of smoke may actually increase in cost/value due to a scarcity of unaffected properties that are now available.