Well, both of my male Akitas have never even acknowledged that thunder occurs unless it startled them out of a sleep. Then it gets a 'who goes there?' WOOF. My first girl tho hated thunder and would stick by my side during a storm. It helped her a lot. My current female started acting like thunder made her nervous when she hit about 3 years and I did the training below. She has ZERO problems with thunder now.(she will ocassionally come and sit with me in the same room during a bad storm tho)
Spend time with your dog during and BEFORE the storm. You can see when thunder is gonna occur before it does (remember lightning?) and immediately start telling your dog what a good girl she is and giving treats. Train her to associate good times with the thunder.