I've seen that sentiment expressed by others, including some experts, but I don't see how it's based in reality. One of the worst outbreaks is in Singapore, and it's practically on the equator.
Apparently the seasonal pattern of colds has never been fully explained. Colds show a seasonal pattern in places like Singapore, just like in Seattle.
Since SARS is related to a cold virus, we can hope it will show the same pattern. Only time will tell.
If it DOES show a seasonal pattern, perhaps we will have a fast, reliable, and cheap diagnostic test by the time the next cold season starts. That would make it much easier to isolate the people who have it.