What is the ignition temperature of paper?

Paper ignites without an external flame in a range of 424 to 475 degrees Fahrenheit. This is known as the autoignition temperature, and it varies with the atmospheric pressure, humidity, altitude and oxygen content of the environment.

Generally, the autoignition temperature of a substance decreases with an increase of oxygen concentration and a decrease of humidity. Traditionally, paper is said to ignite at 451 degrees Fahrenheit, which is an approximate average of the range. Noted American science fiction author Ray Bradbury wrote a book titled "Fahrenheit 451," in which a dystopic government burns books. The autoignition temperature of paper is referenced several times throughout the novel.