From your description of the weather I am going to assume your roses are suffering from a fungal disease such as black spot, powdery mildew or a virus. Rain and wet foliage causes an outbreak of these diseases. Perhaps if you sent a photo I could do a better job of diagnosing the exact problem. Good air circulation and full sun are important but chosing roses for your climate that are disease resistant is the most effective way to enjoy healthy roses. You can always try cutting back the infected part of the roses and fertilizing with Osmocote to encourage fresh new growth that might be less infected. Keep growing, Marianne Binetti