In Pokemon Red/Blue, Charizard's pokedex entry states: "It spits fire that is hot enough to melt boulders." 

On average, the temperature it would take to melt stone into magma would be between 1300-2400 degrees Fahrenheit. That means Charizard's breath ranges from 1300-2400 degrees. At this temperature, a human body in it's entirety would melt also.