The state of Texas lies within both "cool" and "warm" parts of the Temperate Zone of the Northern Hemisphere. Texas has three major climatic types which are classified as Continental, Mountain, and Modified Marine. There are no distinct boundaries which divide these climate types, but the approximate area of Texas that each encompasses is indicated on the following map by the broad stippled lines.
 
 

A Continental Steppe climate is prevalent in the Texas High Plains. This climate type is typical of interiors of continents and is characterized by large variations in the magnitude of ranges of daily temperature extremes, low relative humidity, and irregularly spaced rainfall of moderate amounts. The main feature of this climate in Texas is semi-arid with mild winters.

The Mountain climate is dominant in the Guadalupe, Davis and Chisos Mountains of the Trans-Pecos region of Texas. The characteristics of this climate are cooler temperatures, lower relative humidity, orographic precipitation anomalies and less dense air. The mountain climate is contrasted by the Subtropical Arid climate of the surrounding lowlands.

Most of the state, climatologically, has a Modified Marine climate which is classified and named "Subtropical," with four subheadings. A marine climate is caused by the predominant onshore flow of tropical maritime air from the Gulf of Mexico. The onshore flow is modified by a decrease in moisture content from east to west and by intermittent seasonal intrusions of continental air. The four subheadings of Subtropical - Humid, Subhumid, Semi-arid, and Arid - account for the changes in moisture content of the northward flow of Gulf air across the state.

The climatic descriptions of the regions delineated on the map are given below:

• The eastern third of Texas has a Subtropical Humid climate that is most noted for warm summers.
• The central third of Texas has a Subtropical Subhumid climate characterized by hot summers and dry winters.
• The broad swath of Texas from the mid-Rio Grande Valley to the Pecos Valley has a Subtropical Steppe climate and is typified by semi-arid to arid conditions.
• The basin and plateau region of the Trans-Pecos features a Subtropical Arid climate that is marked by summertime precipitation anomalies of the mountain relief.
• A Mountain type climate is common in the higher elevations of the Guadalupe, Davis and Chisos Mountains.