you didnt say if he has always been like it, or has it progressed with age? if so, he could be just gettin too old n senile. in that case, dont give him tinnned food if possible. its the same for humans. tins give poison off that causes diseses like alchzeimers, n dead dogs are actually in tinned food, incl their collars, chips etc, when theyre destroyed.
I think it would be safe to ignore the answer by inthebegin.
Your vet may be able to help you desensitise your dog to the noise - there are pheromone adapted things that you can get to calm the dogs nerves and there are CDs available that can gradually get your dog used to the noise.
However your dog is getting on in years and it is possible that this is a major factor in the problem.
Your dog will also be able to pick up on any anxieties that you have about the weather - and that could make him worse.
I have found if you give them too much reassurance they are worse, as then they think there really is something to be frightened of. I found Rescue Remedy helped calm mine a lot, and you could also try one of the de sensitising CD's.