There are three main geographic areas in Oklahoma. The Interior Highlands in eastern Oklahoma; the Atlantic Plain in the southeast; and the Interior Plains in the north and western parts of the state. There are many smaller regions within these larger areas. In the south are three mountainous areas—the Ouachita, Arbuckle, and Wichita mountains. These mountains have poor soil for farming, but are popular tourist and recreation areas. The northeastern Ozark Plateau has rough terrain and small fields where fruits and vegetables are grown. Lead and zinc were once mined here, and it has many beautiful rivers that are popular recreation and tourist attractions. The Sandstone Hills stretch through the east-central part of the state between the Red River and the Kansas border. This area has important oil, gas, and coal fields. The Gypsum Hills section of western Oklahoma has large farms growing mainly wheat and cotton. The Red River Plains was once the best farmland in the state, but the soil has been depleted. The Prairie Plains region in the northeast has many oil and gas fields and middle-sized towns. The Red Beds Plains run through the middle of the state. Many of Oklahoma’s larger towns are located there. The sparsely populated High Plains region includes the Panhandle and has the highest elevation and the least moisture of all the regions of Oklahoma. The low point in the state is Little River, in the southeast (289 feet/88 meters); and the highest is Black Mesa, on the tip of the panhandle (4,973 feet/1,517 meters).
The two largest rivers in Oklahoma are the Arkansas and Red rivers. Tributaries of the Arkansas River include the Verdigris, Grand (Neosho), and Illinois rivers in the north and northeast, and the Cimarron and Canadian rivers in the northwest and west. Major tributaries of the Red River include the Washita, Salt Fork, Blue, and Kiamichi rivers. Most of Oklahoma’s lakes and reservoirs were created by building dams on rivers and streams to control floods, generate power, or to use for recreation. The largest of these artificial lakes and reservoirs is Lake Texoma, on the Texas-Oklahoma border. It was created by a dam on the Red River, in Texas. The only natural lakes in Oklahoma are oxbow lakes and playas, which usually evaporate for at least a portion of the year.
Oklahoma has a continental climate with cold winters and hot summers. The average annual temperature is about 60 °F (16 °C), but the temperatures get warmer as you move from northwest to southeast. Oklahoma is also where colder air from the north meets warmer air from the south, and this causes sudden rises and falls in temperature, heavy thunderstorms, blizzards, and tornadoes. The record low temperature of –27°F (–33°C) was set at Watts on 18 January 1930; the record high, 120°F (49°C), occurred at Tipton on 27 June 1994. Average yearly rainfall varies from more than 45 inches (1,140 mm) in the Ouachitas to less than 16 inches (400 mm) in the Panhandle. The western areas of the state are drier than the east. Oklahoma City is one of the windiest cities in the US, with an average annual wind speed of 12.3 mph (19.8 km/hr).
