People of the Lightning by Kathleen O'Neal Gear & W. Michael Gear, Book 7 of North American's Forgotten Past Series, published by Tor Books, paperback.
People of the Lightning takes us to ancient Florida, to a village of fisher folk who must face their deepest fear: Pondwader, now a lanky boy of fifteen summers. He is the White Lightning Boy--the first of his kind to be born in tens of tens of summers. His white hair, pink eyes, and pale skin make him fearsome enough, but legends foretell that a Lightning Boy will make Sister Moon bury her face in the clouds and weep falling stars--and the winds of destruction will be unleashed.

The folk manage to trade him in marriage to Musselwhite, a woman warrior who does not really want him. She must face an old enemy who has captured her beloved husband, an enemy who is determined to destroy her. What good to her is this soft-hearted youth? She has yet to learn that Pondwader is a Lightning Boy. He can hear voices in the wind, telling of coming horror....