WIKI QUOTE:
Certain ratios of these materials will provide beneficial bacteria with the nutrients to work at a rate that will heat up the pile. In that process much water will be released as vapor ("steam"), and the oxygen will be quickly depleted, explaining the need to actively manage the pile. The hotter the pile gets, the more often added air and water is necessary; the air/water balance is critical to maintaining high temperatures (135�-160� Fahrenheit) until the materials are broken down. At the same time, too much air or water also slows the process, as does too much carbon (or too little nitrogen).

No compost will ever spontaneous ignite at 160 Fahrenheit.

Lloyd

I've had piles with too much grass go up to 180 before. The compost was fine but I could have added more browns to make better use of the greens.

While 160 (or even 180) theoretically will never catch fire, somehow compost piles do on occasion. They are usually big industrial ones, so you don't really have to worry at home. I do wonder how they catch fire at all. There must be something going on besides the overall temp - but that's what's so insidious about spontaneous combustion.

"While 160 (or even 180) theoretically will never catch fire spontaneously combust...."

but some will misinterpret.

Lloyd