Many dog owners have no trouble believing that their pets can sense thunderstorms. It's all too common to be awakened at night by an anxious dog only to hear thunder half an hour later. Stories abound about distressed dogs alerting people that a tornado is coming. If your dog is trying to crawl under the couch, it may be time to take everybody to that interior room without windows.
For those who know what to look for, dogs also may predict other changes in the weather, such as a snowfall or the approach of rain. With thunderstorms and tornadoes, a dog's keen hearing – about 20 times as good as ours – comes into play.
There are also good, scientific explanations for why a dog can sense other changes in the weather. Dogs have much keener hearing than humans, of course, but their other sense are also sharper than ours.
Before the weather changes, there are changes in barometric pressure and in the static electricity in the air. Some humans are somewhat sensitive to these changes – think people who get headaches when a low-pressure system is on the way. Dogs are even more so. And the sense of smell can come into play as well. Some people say they can smell rain in the air. What they smell is chemical changes in the air; dogs, with their more sensitive noses, smell the changes even more. And dogs can smell the ozone in the air created by the electricity in lightning – even lightning that we don't yet see. Research suggests that the more dogs experience weather changes, the more they learn about the signs they sense. [source: Greco]