Set up a safe haven in the house. This should be a comfortable snug space, such as a crate, in a room that has minimal sound penetration from the outside, such as a basement or closet. Practice a routine of going into the safe place and give your dog a favorite treat or toy. You can play music to disguise the noise of the storm or fireworks. Recordings of storms or fireworks are available. Playing these at a soft volume while bringing your dog to the safe will help them become used to the sounds during positive activities.
There are products available that can help many dogs. Mutt Muffs® are noise-blocking ear muffs for dogs available in different sizes at safeandsoundpets.com and can really help some doggies. Many dogs will feel safer in a snug wrap such as a Thunder Shirt® available at thundershirt.com. A product called Adaptil is available at adaptil.com as a spray, diffuser or collar. This pheromone (communication scent) tells dogs that everything is OK and reduces anxiety making their environment more calming and welcoming.
Dog owners that have very anxious or panic-prone dogs should not hesitate to seek advice from their veterinarian. It is important to help dogs with their anxiety. Untreated severe anxiety is prone to escalate with each exposure to the stimulus. There are short-acting anti-anxiety drugs that can give tremendous relief to dogs when given a short while prior to fireworks or thunderstorms. For dogs that are very anxious in general and panic-stricken during storms there are other drugs to help control anxiety at all times.