Generally, annual precipitation decreases about an inch for each fifteen-mile displacement from east to west. The mean annual rainfall distribution correlates roughly with longitude and varies little from north to south across Texas. The mean annual precipitation varies from a statewide maximum of 59.20 inches at Orange, in the lower Sabine River valley of East Texas, to a minimum of 7.82 inches at El Paso, at the western tip of the state. Precipitation is not evenly distributed over the state, and variations in precipitation at any one locale from year to year are apt to be pronounced. Though variations in climate across Texas are considerable, they are nonetheless gradual. The eastern two-thirds of Texas, on the other hand, has a humid, subtropical climate that is occasionally interrupted by intrusions of cold air from the north. In the Trans-Pecos, a form of mountain climate is found.

West of the Caprock on the High Plains, a continental climate, marked by cold winters and low humidity, predominates. Because of its expansive and topographically diverse nature, Texas offers continental, marine, and mountain-type climates. The state's varied physiography, from the forests of the east and the Coastal Plain in the south to the elevated plateaus and basins in the north and west, also brings a wide variety of weather on almost any day of the year. The location of Texas with relation to the North American continent, the warm Gulf of Mexico, and the not-far-distant Pacific Ocean guarantees a constant exchange of settled and unstable weather.

Texas precipitation totals