Thank you for your question.
Dogs naturally have a higher temperature than we do, so they will always feel a little warm. Our normal temperature is around 98°, and their normal temperature is around 101°. Whether the nose is dry or wet does not indicate if your dog has a fever. Just like you, the only real way to know if your dog has a fever is to take it's temperature. Don't put a thermometer in your dog's mouth because it might get broken or eaten! The way we do this at the veterinarian's office is to use one rectally. If you are really interested, you can get a thermometer specifically for your dog and have your veterinarian show you how to take the temperature.
Besides taking the temperature, most dogs with a fever tend to lay around. They have a decreased appetite. And don't want to go outside and play. Just like you feel when you have a fever. If you see these signs, it is better to take your dog to the veterinarian and let them check it out.