Where I live, fire season used to be just a few months out of the year. No open flames during that time. Then it was extended a month at the beginning and end, then another month, and now it's all year depending on conditions.
It should be noted that 85%+ of forest fires in the US were due to humans. In Turkey it was estimated to be 95%. Spain is battling arsonists behind hundreds of wildfires and described it as a terror attack. Granted, warmer climate makes it easier for fire to spread but it's not like the earth has started to self combust.
By number or by area burned? - Either way can you cite your source for your figures?
It seems at odds with, for example, these quotes (of which there are many):
> Lightning remains a major cause of wildfires and the storms that have passed through Northern California are wreaking havoc for firefighters. [1]
> Lightning ignition explained more than 55% of the interannual variability in burned area, and was correlated with temperature and precipitation, which are projected to increase by mid-century. [2]
> Human-started wildfires accounted for 84% of all wildfires, tripled the length of the fire season, dominated an area seven times greater than that affected by lightning fires, and were responsible for nearly half of all area burned.
So human activity accounted for 84% of ignitions of 'significant' fires within coterminous United States during the twenty one year period [1992-2012] (inclusive).
Those fires ignited as a result of human activity accounted for 44% of total area burned.
Human activity as a source of ignition includes
> a variety of sources, including the US Forest Service-designated categories of equipment use, smoking, campfire, railroad, arson, debris burning, children, fireworks, power line, structure, and miscellaneous fires.
I'd suggest that it's important to point out that more than half of wild area burned doesn't result from human activity and that human arson is a small portion of human ignition sources (which is not at all how your intial comment reads).
I do agree that the biggest issue here is the effect of changing climate increasing the chances of wildfires both in areas traditionally prone and in areas that have rarely seen them.