Several methods have been used to define the subtropical climate. The most well known is the Trewartha climate classification, which defines a subtropical region as one that has at least eight months with a mean temperature greater than and at least one month with a mean temperature under . In most regions in this climate zone the coldest month has a mean temperature of above . In the Trewartha climate classification, most of these climates are located in the most equatorial portions of the temperate zone (latitudes between 23.5° and 35° north and south).