The hot and humid days of summer could prove a death knell for the swine flu outbreak currently sweeping around the globe–at least in the U.S., Mexico, and the rest of the Northern Hemisphere, experts say.

“If [the new swine flu strain] is like other types of influenza that have been tested, it would have a lower transmission rate in the summer,” said Jeffrey Shaman, an assistant professor at Oregon State University in Corvallis, who studies how the water cycle affects the spread of disease.