You did not mention the age or breed of your dog. Also, he is current on his heartworm testing and preventative?
If he is young and has been healthy, and is not having any changes in his breathing pattern between the coughing episodes, there is a good chance that you may be dealing with kennel cough. Has he been around other dogs recently, such as at the groomer or at a kennel or even a public dog park? This is a highly contagious disease and spreads from dog to dog through the air. Luckily, most of the time it is not too serious, they just do a lot of coughing, but continue to feel good and eat well. Many of these dogs will go into a coughing spasm if you put a little bit of pressure on the under side of their neck over the trachea (wind pipe). On occasion though, it can turn into an pneumonia situation. We usually treat these with antibiotics and sometimes cough suppressants.
If your pet is older and/or has ever been diagnosed with a heart murmur, then I would be more concerned. Coughing can be due to a build of fluid in the lungs if the heart is not working normally and this is potentially much more serious.
Other causes of coughing would include bronchitis, or allergic airway disease, heartworm disease and collapsing trachea. There is a relatively new disease called canine influenza that can look like kennel cough initially but has the potential to develop into a more serious illness. There is a blood test that can be done, but it will have to be sent away to an outside lab and will take several days to get back.
If this is kennel cough, while it is not really an emergency, it is an infection and with all infections, treating earlier is better than treating later. Coughing due to a heart problem would definitely be considered an emergency as these dogs can get into a crisis quickly.
I would tend to err on the side of safety and have him seen this weekend. If your vet happens to have hours on Sunday and your dog's breathing pattern is normal and he is young with no heart murmur, it would likely be okay to wait until tomorrow, but I would hate to wait until Monday even if this was kennel cough as this just gives the infection longer to get established. If your dog is not current on heartworm preventive and you live in the south where heartworm is extremely common, take him in immediately.
I hope this answers your questions. If so, please click "Accept." If not or if you have additional questions, please let me know.