Suede is a very delicate and soft material that can become damaged if exposed to too much moisture; because of this, it is not advised to wear suede out in the rain unless proper precautions are taken first. Many suede and leather companies sell protective spray designed specifically to protect suede when it is raining.
When suede gets wet, the first thing that happens is that it loses its texture. Because suede is so soft, this is very noticeable to anyone in physical contact with the material. If the suede gets too wet, it can then stain, sometimes permanently, if the stain is bad enough. Because of this, its best to sport a different material in the rain, or use the above-mentioned protective spray.