Dictionary.com- Apt to change suddenly; whimsical; changeable.
Wiktionary- Impulsive and unpredictable; determined by chance, impulse, or whim; as, a capricious winterstorm, stringent rulers often act capriciously.
“Molly was a capricious woman. Her moods were unpredictable, her anger petty and vicious.”
Rand Roberts and James Olson, John Wayne: American