Weatherfoul (3.5e Flaw)
From D&D Wiki
Through a lifetime of living in relatively calm conditions, you suffer from lack of experience with foul weather.
Effect: In inclement weather or storms, all terrain is considered difficult terrain, costing double movement. In normally difficult terrain, this flaw only allows a single square of movement.
Normal: Difficult terrain is usually limited to overgrowth, heavy brush, and other extreme conditions, and cost double movement per square.
Roleplaying Ideas: A person who has grown up in Tirasus, which is blessed with relatively calm weather all year long, venturing out into the world, and being completely taken aback by the naturally turbulent weather outside of his shelter.