There are three stages of heat in the home composting process:
The initial phase is where mesophilic microorganisms, that love medium-heat and thermophilic microorganisms, that love high-heat show rapid growth in numbers.
This next phase is when most of the composting takes place and where temperatures reach the highest. Some mesophilic microorganisms may survive the heat, but there is now a dominance of high-heat loving bacteria, fungi and actinomycetes.
Once the temperature is around 70˚C, the compost is sanitised as pathogens die. These conditions also kill seeds of weeds, so the compost is suitable to be a fertiliser.
The final thermal phase is maturation, when the composting procedure slows down and the temperature begins to drop. Once cooled, the compost will be ready for you to use in your garden.