Despite differing opinions on the topic, Colorado's monsoon season is already underway, according to Klaus Wolter, an atmospheric scientist at the University of Colorado at Boulder. In fact, Wolter believes the Southwest monsoon began early this year. The monsoon season, which typically starts around the middle of July in Colorado, actually began at the beginning of the month, said Wolter, a researcher with the Climate Diagnostics Center, part of the Cooperative Institute for Research in Environmental Sciences at CU-Boulder.