Question: How hot does fire have to be to make a flame?

Sam Geen answered on 11 Nov 2020:

You need two things to make a flame – enough temperature to burn something, and enough temperature to make it glow. The glowing is because electrons in the atoms being heated by the fire get given energy by the heat, and when they lose the energy they produce photons, which is what makes up light. The more energy in this, the bluer the light. The glowing part will be about 700 degrees C to make a red flame, or around 1500 degrees C for blue flames, but you can set fire to paper at above 250 degrees C. Once something starts burning it makes more energy, so can get hotter. This is why fire is dangerous – a small flame can catch a lot of things on fire.