There are usually 3 reasons to give a player a specific weather effect:
1. Weather can boost the potency for magic that matches the element. Nukes of the matching element can get a straight increase in damage (+10% for single weather, +25% for double weather). Cures with light weather can get an increase in HP healed. Elemental Obis from Sea make these bonuses active 100% of the time, whereas without the Obis the bonus kicks in around 25% of the time.
2. When Stormsurge is meritted by the SCH, the player receiving the storm effect also gets attribute bonuses to go with the element. For instance, melee DDs who receive firestorm also get +STR from it.
3. Weather can trigger bonuses on certain pieces of gear. Most SCHs carry around Desert Boots, which grants +movement speed when the player is under earth weather.
Lyonheart of Lakshmi
lvl 99 NIN WAR BST THF BLM SCH WHM
1/467 on signed HQ Weskit!!!