Like people who can predict weather changes based on how their bodies feel -- sinus pressure, aches and pains -- dogs have an uncanny ability to note changes in air pressure via their senses. In particular, when pressure drops, indicating cloudy and rainy weather, your dog might be more accurate than the TV weatherman.
A barometer is a gauge that measures air pressure. When the pressure rises, the air pressure increases; when pressure falls, or drops, air pressure decreases. Rising or falling pressures affect daily weather. Typically, a high-pressure means clear weather, while a low-pressure usually means clouds, rain, snow or other weather events are imminent. Like that gauge, your dog uses his senses of hearing and smelling to monitor the change in air pressure and, hence, weather changes.
The Nose Knows
Dog owners know how much their canines rely on their snouts to sniff out food, as well as other dogs, people or animals. That's because a dog's nose is more sensitive to chemicals than a human's nose. So if you step outside and smell rain in the air, your dog -- via his sense of smell -- has long detected it before you did -- not to mention ozone, which signals that lightning is in the area.
The Ears Have It
Dogs also have highly sensitive ears allowing them to detect sounds near and far. For instance, your dog can hear thunder in the distance -- long before you'll hear it. That's because a dog's hearing is almost 20 times more sensitive than ours, according to nationally known dog trainer Cesar Milan. A dog's ears can pick up vibrations in the air even before the thunder arrives, which is why dogs are often frightened of oncoming storms.
1 + 1 = 2
Patricia McConnell, a noted canine behaviorist and author, says a dog's change in behavior due to pressure drops is a result of "backward chaining." In other words, dogs react to stimuli that predict another outcome. For example, a dog may be afraid of thunder, but the wind before the thunder triggers the dog's fearful response to barometric pressure variations.