White dragons can be split into two symbolic groups: lunar-white and solar-white.
Solar-white dragons are imbued with the power the sun, a symbol of holiness and purity. A solar-white dragon is associated with a sun god or a powerful god of creation.
A lunar-white dragon symbolizes death and rebirth. It embodies a dangerous and ferocious supernatural power, likely associated with a moon god or a mother goddess.
In China, a white dragon is an omen of death, a warning. White dragons are associated with the direction south.
Dragons of Fame: Pai Lung, O Goncho
~ Article courtesy of http://www.blackdrago.com/colors_white.htm