The Arkansas River flows across the southern part of the highlands and the Missouri River across the northern. The only major river which passes through the Ozark Plateau and Ouachita Mountains is the middle Arkansas. The Ozark Plateau and Ouachita Mountains are known for their many scenic, small spring-fed streams. The ground water of the Ozark Plateau and Ouachita Mountains exists as the confined Ozark aquifer from which water is extracted for a wide range of uses such as irrigation, livestock watering, and municipal water supplies. The area has hot summers and varies between mild and cold winters.
Rainfall occurs throughout the year, with drier periods in summer and autumn.
The Ozark Highlands support oak-hickory forest. The primary overstory species are red oak, white oak, and hickory. Shortleaf pine and eastern redcedar are important on disturbed sites, shallow soils, and south- and westfacing slopes. The primary overstory species are southern red oak, black oak, white oak, and hickories. Shortleaf pine and loblolly pine may constitute as much as 40 percent of the cover.