The correct use of "blonde" is for a woman with yellow hair for males, it's "blond." The terms aren't completely synonymous.
The term comes from Old French's "blund" which literally means midway between gold and light chestnut.
This means that blond and blonde are one of the few word in English that has gender differentiation.
While in other languages it's pretty common (for example, in Spanish it would be rubio and rubia), English has very few words that change when used for the male and female gender