White flames are the hottest color of fire that can be achieved by burning organic matter, while red flames have the lowest temperature. The scale for flame colors on organic mediums moves from red to white, meaning orange is hotter than red, yellow is hotter than orange and white is hotter than yellow.
For non-organic burning, such as gas or other chemicals, the range includes blue. Blue flames are hotter than white ones. The more white a non-organic flame has, the cooler it is, while more blue indicates a higher temperature.Learn more about Physics