Why does my Staffie get hyper just before it rains?

All dogs can since if it is going to storm my dogs are afraid of thunder infact it is a animals nature to since if a storm is coming just like with cows or anything.Have you eve seen cows all bunched together that is because they know a storm is coming. My Grandpa told me that years ago when I was just a lttle girl and I ask him why the cows was standing like that