It's very common for dogs to be afraid of lightning, and it’s a fear driven by a combination of sensory overload and instinct. This fear, often called astraphobia, isn't just about the visual flash.
A dog's hearing is far more sensitive than a human's. They can hear the low-frequency rumbles of distant thunder long before we can, creating an early sense of anxiety. When the storm is closer, the loud, sharp crack of thunder can be physically painful and startling to their sensitive ears.
Beyond the sound, dogs can also sense other atmospheric changes associated with a storm. They are sensitive to drops in barometric pressure and the build-up of static electricity in the air. This static can create an uncomfortable tingling sensation on their fur and skin. Some dogs may even receive small, unpleasant static shocks. This physical discomfort, combined with the unsettling sounds, leads them to associate the entire storm experience—including the flash of lightning that precedes the thunder—with something negative and threatening.
This fear is also partly instinctual. In the wild, loud noises and dramatic weather signal potential danger, prompting a "seek shelter" response. Your dog isn't being irrational; they are reacting to a powerful sensory experience that their instincts tell them is a threat. Providing a safe, comforting space like a crate or a quiet room during a storm can help manage their anxiety by giving them a secure place to retreat.