People with natural curls and/or coarse hair tend to end up with frizzy hair. It could be due to a lack of moisture from overexposure to humidity, sun and strong wind, or you could be facing severely damaged hair which is usually porous and absorbs too much moisture.
On the other hand, your frizzy mane could simply be hereditary, which is absolutely gorgeous. Still, if you desire to de-frizz your hair, look to hair products specially formulated for frizzy hair, and prevent further exposure to heat by using suitable hair styling products.