coreyes wrote:

I know this is controversial, but I actually don't believe the bit about fires being lit deliberately, well not as many as they say anyway. Hit 44'C and fires just break out everywhere. Self igniting, I believe.
I don't know that it's controversial Coreyes. While there is no doubt that some fires are deliberately lit by arsonists, I suspect they do inflate the figures a bit to maximise the fear factor. And how do they actually work out the stats? For example, is a cigarette butt out the window of a car counted as deliberate or accidental? Some would say deliberate, although perhaps there wasn't an intent to start a fire, the action was deliberate and the person should have known better. Friction between hot metal surfaces is also is a culprit. Heat lightning and storm lightning start a lot of fires (like Canberra's) and, as you say, just the heat itself - self-combustion of a dry substance.

I think the major point is that any fire started by an arsonist is one too many and can/will cause just as much damage and loss as a natural one.