I never did a lot of temp checking on my pile, but I don't think it would make it that high. I am still not convinced they combust because of heat from the composting process. Has this ever been proven in a lab condition? I haven't studied up on it but here are my thoughts. There could be so many causes and they can smolder so slowly it would be hard to say what caused ignition I would think. Think of it. All of the equipment used in blowing, gathering, transporting, shredding, or turning can emit a tiny spark from their exhausts (fire up one of your mowers at night and watch the sparks fly), a cig butt, a meteor fragment, lightning, static spark, fireplaces and firepits. A pile that is dry enough to ignite - could it get that hot since it is not cooking properly from being so dry? The dry outside could easily ignite but that is not where the heat is. I once put out a neighbors burning leaf and clipping pile two days after I watched them dump their grill ashes on it. This was not a real compost pile as they never tended to it, but just dumped stuff on it. It took that long for it to build up to a point that I could see and smell some small amount of smoke. As I turned it though it was more active underneath. As one of the links I put up above states, once past 155 or so, many of the bacteria will begin to die off and the temps drop until it balances back out and rebuilds. I would imagine a pile would max out around the 190-200 mark due to that self regulation, but then I am no expert. I do have good success with my pile though and always see substantial growth and color changes in whatever I add it too, be it topdressing the lawn before it comes to life in the spring or placing in with container plants or on the garden and beds. If I topdress turf in late winter, it revives nearly two weeks sooner than areas I do not get covered. I get bedding and manure from local stables maybe twice a year, and add my own clippings and leaves and appropriate kitchen scraps, ocassional water hyacinths and wood chips, deadheading scraps and fall clean up, weeds and sod trimmings, fire pit ashes, and soil from container plants at the end of the season. I've had piles ready in as little as two to three weeks, when I was able to turn them daily. The pile is too big now for daily hand turning so it's a slow cooker.