Dogs flying internationally in AUGUST. Are there written regulations?

My dog can either come now which is very hard because he has to fly by himself and it's double the cost. Or come back with me in August. We are flying out of Seattle, WA to Seoul, Korea. I would think since he has to ride in the Cargo area and it's climate controlled it would be fine because it's a huge plane. Does anyone know where there are any written regulations about the weather and restrictions I can't seem to find any anywhere. We have all of the stuff done to get him here it's just the flying part that's been so difficult to schedule.