Arctic Winds

Arctic Winds is a mage talent that increases all Frost damage done and reduces melee and ranged opponent's chance to hit by 1% per rank, up to 5% at rank 5. This talent is popular with frost mages that want to get the most damage out of their frost spells, as it is a direct boost to all Frost damage. The chance to hit reduction effectively reduces hit rating from melee and ranged attackers, reducing damage taken, making this a useful PvP talent as well. Damage from warriors, rogues, hunters, and some shamans, druids and paladins will be affected the most.

This stacks with a similar talent in the Frost tree Piercing Ice, which also increases all Frost damage done by 2% per rank, up to 6%. The damage increase for this talent works the same, by including all spell damage gear the mage is wearing. Since it is a multiplicative increase, the combined effect of the talents combined is an increase of 11.3% to all frost damage (after the addition of +damage from items). With Curse of the Elements applied to the target this gives an effective increase of 22.43% (25.70% with 3/3 Malediction) to all frost damage.

This talent doesn't affect the damage numbers which show in the tooltips of your frost spells.

The damage multiplier applies to total damage, including the base damage, bonus from spell damage gear, and any other damage multipliers. The following formula gives the total damage of a frost spell, E, where B is the spell's base damage, c is the spell damage coefficient, d is the amount of spell damage the mage has, and Y is the number of points in Arctic Winds. Critical strikes are not considered.

E = (1.0 + 0.01*Y)(B + c*d)

Piercing Ice is a second multiplier applied in a similar way. The following formula includes X, the number of points in Piercing Ice.

E = (1.0 + 0.01*Y)(1.0 + 0.02*X)(B + c*d)

Past changes
This talent was introduced with Patch 2.0. Originally, it only affected enemy chance to hit. With Patch 2.1 the damage increase was added.