Climate of Texas Introduction This publication consists of a narrative that describes some of the principal climatic features and a number of climatological summaries for stations in various geographic regions of the State. The detailed information presented should be sufficient for general use; however, some users may require additional information. The National Climatic Data Center (NCDC) located in Asheville, North Carolina is authorized to perform special services for other government agencies and for private clients at the expense of the requester. The amount charged in all cases is intended to solely defray the expenses incurred by the government in satisfying such specific requests to the best of its ability. It is essential that requesters furnish the NCDC with a precise statement describing the problem so that a mutual understanding of the specifications is reached. Unpublished climatological summaries have been prepared for a wide variety of users to fit specific applications. These include wind and temperature studies at airports, heating and cooling degree day information for energy studies, and many others. Tabulations produced as by-products of major products often contain information useful for unrelated special problems. The Means and Extremes of meteorological variables in the Climatography of the U.S. No.20 series are recorded by observers in the cooperative network. The Normals, Means and Extremes in the Local Climatological Data, annuals are computed from observations taken primarily at airports. The editor of this publication expresses his thanks to those State Climatologists, who, over the years, have made significant and lasting contributions toward the development of this very useful series. State and Station Normals are available at: http://cdo.ncdc.noaa.gov/cgi-bin/climatenormals/climatenormals.pl Visit our Web Site for other weather data: www.ncdc.noaa.gov Non-Subscription Request: Hard Copy Subscription Request: Climate Services Branch NCDC Subscripting Service Center National Climatic Data Center 310 State Route 956 151 Patton Avenue Building 300 Asheville, North Carolina 28801-5001 Rocket Center, West Virginia 26726 Telephone: 828-271-4800 Toll-Free Telephone: Facsimile: 828-271-4876 866-742-3322 E-mail: [email protected] TDD: 828-271-4010 Climate of Texas Topographic Features- Texas is the second largest state in the United States, with a total land area of 267,340 square miles, roughly equal to the combined area of New England, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, and North Carolina. About 800 miles separate its northernmost and southernmost points, as well as its westernmost and easternmost points. It is also the second most populous state, and its population density almost exactly equals the national average. Like California, its residents are unevenly distributed. Large stretches of land have less than one person per square mile, but Texas also includes several of the country’s most populous metropolitan areas including: Dallas – Fort Worth, San Antonio, Houston and Austin. Texas contains the largest acreage of cropland in the United States, as well as the largest amounts of pastureland and rangeland. While most of the State is rural, Texas is occupied by the largest amount of urban land of any state. Meanwhile, Texas is second only to Alaska in the amount of the state covered by inland water. The State has variations in geography commensurate with its size and diverse character. Perhaps the most distinctive region of the State is the portion west of the Pecos River, which is known as the Trans-Pecos or Far West Texas. Far West Texas has a Basin and Range topography similar to much of New Mexico, Arizona and Nevada and, like sections of New Mexico and Arizona; it is part of the Chihuahuan Desert. The tallest mountain range is the Guadalupe Range, composed of an ancient coral reef. Guadalupe Peak is 8,749 feet above sea level and is the highest point in Texas. The range is contained in Guadalupe National Park, one of two national parks in Texas. The other, also in Far West Texas, is Big Bend National Park, which contains the Chisos Mountains, several other mountain ranges, and the United States side of three deep canyons along the Rio Grande. The second tallest range is the Davis Mountains, which has the McDonald Observatory. The climate of Far West Texas has a climate more similar to New Mexico than to the rest of Texas. Winters are cold and generally dry, except for rain and snow that fall mostly in the higher elevations. Summer is the rainy season, and moisture from both the Gulf of Mexico and the Gulf of California contribute to afternoon thunderstorms. Annual precipitation depends on elevation more than location; the dry grasslands near Marfa that form the backdrop of the movie Giant do not resemble the rest of the State but have become part of the public consciousness of the Texas natural environment. Other parts of Texas have neither the topographic relief nor the wide variations of climate of Far West Texas. The terrain changes steadily and continuously from one end of the State to the other, the terrain interrupted only by such features as the Caprock Escarpment (in the Panhandle) and the Balcones Escarpment (along the southern and eastern margin of the hill country). The - 1 - terrain descends from northwest to southeast, drained into the Gulf of Mexico by a series of parallel rivers. From the Mexican border to the Oklahoma border, they are the: Rio Grande, Nueces, Guadalupe (which is not near the Guadalupe Range), Colorado (which is not near the Grand Canyon), Brazos, Trinity, Sabine and Red. Other notable rivers include the Pecos, which empties into the Rio Grande, the San Antonio, which empties into the Guadalupe, the San Jacinto, which empties into Galveston Bay, the Neches, which empties into the Sabine, and the Canadian, which flows across the Panhandle from New Mexico to Oklahoma. Seven of these rivers are more than 500 miles long. The climate changes are even more gradual than the terrain. Annual mean temperatures are coolest to the north and warmest to the south. Annual mean precipitation is heaviest in the east and lightest in the west. Precipitation changes are more substantial than the temperature changes, as the near-desert in the west gradually gives way to annual accumulations close to 60 inches along the Louisiana border. With subtle variations in climate and terrain, sub-regions of the State of Texas are often more clearly delimited by changes in vegetation or terrain character. Because many transitions are gradual, categorizations are somewhat arbitrary. The following 10 regions correspond roughly to the 10 climatic divisions of Texas. The Trans-Pecos region was discussed earlier in this document. Now the other nine will be described. The Texas High Plains occupies most of the Texas Panhandle and is defined on the north and west by the State boundaries and on the east by the Caprock Escarpment. The High Plains are about as flat as the coastal plains of Texas. The major cities of the High Plains are Amarillo, Lubbock, and on the margin of the Trans-Pecos, the neighboring cities of Midland and Odessa. Much of the High Plains is underlain by the Ogalalla Aquifer, which supplies a large but dwindling water supply to the area’s irrigated agriculture. The High Plains are divided in two by a valley carved by the Canadian River, and a branch of the Red River has created the dramatic Palo Duro Canyon. Elsewhere, the High Plains are pockmarked with shallow, intermittent lakes and an occasional district where sand dunes have been set in motion by the wind. The Low Rolling Plains are largely rangeland, consisting of grasslands interspersed with forests of mesquite, a short, invasive tree with sweet-smelling wood but sparse shade. They lie east of the High Plains and include the cities of Abilene and Wichita Falls. While surface waterways are much more numerous than in the High Plains, lakes are much less frequent, as the land drops steadily toward the east. Many soils are quite red, and the runoff from this area helps give the Red River its name. This area has the greatest frequency of tornadoes in Texas. The Cross Timbers are also a mixture of grasslands and forest, although the forest includes oak and other species besides mesquite. The greater biological diversity among trees is attributable to higher precipitation totals and slightly warmer temperatures, along with soil variations. Like the Low Rolling Plains, the Cross Timbers slope mainly from west to east. Most lakes are man- made. Fort Worth and Temple are prominent cities on its eastern edge, while Austin, the State capital, sits at the intersection of the Cross Timbers, the Blackland Prairies, and the Edwards Plateau. - 2 - The Edwards Plateau lies south of the: High Plains, Low Rolling Plains and Cross Timbers, and east of the Trans Pecos. Its southern margin is the Balcones Escarpment, and the region includes both the relatively flat plateau area as well as the high-relief plateau margin where some of the most rugged terrain in Texas (known as the Hill Country) is located. The area is underlain by limestone formations, and many dramatic caves are located here. The vegetation varies from grasslands in the west to forests in the east, with pockets of maple and cypress hundreds of miles from their normal ecosystems. The most prominent city is San Angelo, but its eastern margin abuts Austin and San Antonio and various bedroom communities have developed, attracting people from the cities with its scenic ruggedness and slightly cooler summertime temperatures. Various spring-fed rivers and streams originate along the Balcones Escarpment. The Blackland Prairies are defined by several strips of rich, black soil that extend from San Antonio to Dallas and beyond and eastward to the Piney Woods.