Weather Witch/Warlock

A spellcaster specializing in sea, wind, lightning and storm magic, bolstered by the power of the Eight Sovereign Seas.
Prestige class. Caps at level 10.
Requirements:

Pass the Trials of the Eight Sovereign Seas

Have a patron with a sea/ocean power

Ability to cast lightning or weather related spells.

Progression:

Additional cantrip at level 1, 5 and 10 (per 5th ed, changes to storm themed)

HD d8

Progresses any/all casting classes with access to storm-related magic

Spells per level:
lvl 1: 2
lvl 2: 3
lvl 3: 3 / 1
lvl 4: 4 / 2
lvl 5: 5 / 3 / 1
lvl 6: 5 / 3 / 2
lvl 7: 5 / 4 / 3 / 1
lvl 8: 5 / 5 / 3 / 2
lvl 9: 5 / 5 / 4 / 3 / 1
lvl 10: 5 / 5 / 5 / 4 / 2
Spells must be taken from weather and elemental spheres and storm magic (Tome of Magic and Wizard's Spell Compendium).
Abilities by level:
lvl 1: Clear Sailing: Negates weather related penalties for friendly ship.
lvl 2: Storm Crow: Receive warnings of impending attack or event.
lvl 3: Wilding Waves: Agitate water surface to boost speed and maneuver of friendly ship, reduce for hostile ship.
lvl 4: Weather Sense: Predict and sense weather and magic affecting weather, location of any casters affecting weather.
lvl 5: Divine the Seas: Locate nearby ships/landmasses, sea creatures within 1 mile per caster level.
lvl 6: Ocean's Call: Calls aquatic Beings friendly to caster once per day.
lvl 7: Ocean's Gift: Find treasure as scroll/treasure map once per week.
lvl 8: Weather's Call: Control Weather or summon Strengthened Air Elemental once per day (caster level=HD).
lvl 9: Rogue Wave: Summon a tsunami or summon Strengthened Water Elemental once per day (caster level=HD).
lvl 10: Natural Magic: Lightning/wind/water spells may count as natural, letting them bypass magic resistance.