Snow Cloak (Japanese: ゆきがくれ Hidden in the Snow) is an Ability introduced in Generation IV. Eight Pokémon have this Ability, all of which are Ice-type.
Snow Cloak causes evasion to increase by 20% in a hailstorm. Even if a Pokémon which is not of the Ice-type acquires this Ability, it will be immune to the effects of hail.
If a Pokémon with Snow Cloak is leading the party in an area with a blizzard, then Snow Cloak decreases the wild Pokémon encounter rate by 50%.