My dog is scared of rain/storms?

I've had my dog, Jake, for about a year now. He is a year old and about 25-30 pounds. He is a Yellow Lab/Bloodhound mix. He can be quite aggressive but can be like a teddy bear when he wants to be. The one thing that surprised me was that he was afraid of storms! I know that dogs can sense when rain is coming. And when he senses it, he whines nonstop. He will scratch at the windows and whine. Even if it is only rain he constantly whines, wanting to be put in the garage (he is an outdoor only dog). Especially when there is thunder and lighting he stands at the door leading to the backyard and whines. Is there a way I can help him to not be like this? We worry about him when we are gone if there is rain because when he gets bigger, he is likely to want to jump over the fence and run (although we have put up an electric fence). Please help.