Drought is one of the many abilities that are inheritable by Pokémon.
Function
Drought summons harsh sunlight in battle as soon as a Pokémon with Drought enters the battle. Its effects are the same as the move Sunny Day, and will only last for five turns. This can be extended to eight turns if the Pokémon is holding a Heat Rock. If a Pokémon with Drought is sent out in the same turn as another Pokémon whose Ability affects the weather, the slower Pokémon's Ability will override the faster Pokémon's Ability.
Inheritable Pokémon
Predominant ability
Primary
Secondary
Mega Pokémon
Hidden ability