Astraphobia: An abnormal and persistent fear of thunderstorms. Sufferers experience anxiety even when they realize the risk of harm is very small. Consequently, when indoors they might seek shelter under a bed, in a closet or in a basement. They generally keep a watchful eye on the sky and remain alert for reports of electrical storms.
"Astraphobia" is derived from the Greek "aster" (star) and "phobos" (fear).
Related term: Brontophobia: Fear of thunder.