North American Monsoon - Starts Today

The North American monsoon begins today and lasts through September 30th.  This summer thunderstorm season in the southwest gained its official name in 2004.  Before that, it was called the Mexican monsoon, Southwest monsoon, and Arizona monsoon.

The North American monsoon is a seasonal shift in the winds over the southwestern U.S.  The southerly winds bring humid air from the Gulf of Mexico, Gulf of California, and Pacific Ocean.  The humidity interacts with the heat and terrain to produce thunderstorms.

Before being named the North American monsoon, meteorologists first had to debate whether the Southwest's summer storms were a true monsoon.  The word "monsoon" is derived from the Arabic word "mausim" which means season.  Monsoon season is redundant.

North American monsoon - The weather behind the wind shift.