The Siberian wildfires are in the boreal forest, an environment that needs wildfire to maintain itself, so from that perspective, whether ignited by man or lightning, they are a natural event to a point. But the wildfire fighting community has a bit of a problem; they got too good at it for their own good. Since the end of WWII they got really good at fighting wildfires, finding them early, hitting them hard, using helicopters, air tankers, heavy equipment, and gas powered pumps. Or at least they got really good at fighting the low intensity wildfires who's spread and behaviour were already somewhat limited by small amounts of forest fuel loading in the understory.
On the parts of the landscape with timber we used logging to, in some respects, emulate wildfire. It removes the fuels, we re-establish the trees and keep the forest young. But there are many parts of the landscape, the black spruce bogs, slow growing soil types, steep slopes, sensitive areas, parks, and residential subdivisions in the forest, where, through firefighting, we almost eliminated fire, the landscape. This, in an ecosystem, that relies on fire as a natural disturbance, as it's only natural method to replenish itself. Over this last 70 years the amount of fuels on the landscape has been changing, increasing, well beyond what might be within the natural range of variability.
So now, many of our wildfires in the boreal forest are driven by a much higher fuel loading than they saw before. The network, or patchwork, of small or low intensity wildfires is gone from the landscape, and we experience the mega fire phenomenon. (Google mega fire and you get lots of good reading). These fuel driven mega fires are further complicated by changes in the weather. Wildfire behaviour is incredibly sensitive to relative humidity, temperature, wind speed, and fuel type, and all of these are sensitive to climate change.
One small example of a seemingly minor weather change with big implications. The temperature of our overnight lows seem to be changing, increasing, although our daytime high temps seem less changed, (according to a few small local data sets we looked at, nothing publishable). But this one small change means more frost free days, earlier snow melt in spring, less relative humidity recovery (increase) overnight, a longer effective wildfire burning period during the day, grass curing earlier in the season so more cured (flammable) grass, and I’m sure a whole number of more complications.