This ecoregion extends from Windsor to Toronto, including the Niagara Peninsula at the southern tip of Ontario. The ecoregion has one of the warmest climates in Canada. It is marked by humid, warm to hot summers and mild, snowy winters. The mean annual temperature is approximately 8°C. It reaches as high as 9°C in the Windsor area. The mean summer temperature is 18°C and the mean winter temperature is -2.5°C. The mean annual precipitation ranges 750-900 mm. Precipitation is evenly distributed throughout the year. The dominant land cover is cropped land with limited areas of mixed and deciduous forests on the Niagara Escarpment. Urban development is the other significant land cover. Climax vegetation is characterized by sugar maple, beech, white and red oak, shagbark hickory, black walnut, and butternut. Moist sites are characterized by white elm, eastern cottonwood, balsam poplar, red and black ash, and silver maple. Drier and warmer sites contain black, chestnut, and chinquapin oak. Tulip tree, sycamore, and bitternut hickory occur on moist slopes. The ecoregion is underlain by carbonate-rich, Palaeozoic bedrock and is dominated by a wide variety of deep glacial deposits. Most of the region lies southwest of the Niagara Escarpment, where the land surface slopes gradually southwestward through low-relief, rolling topography. Bedrock outcrops are only in a limited area between Hamilton and Georgetown. The ecoregion east of the escarpment consists of primarily level, fine-textured lacustrine deposits. Minor areas of sandy to loamy till deposits also occur. Clayey Gleysolic and Gray Brown Luvisolic soils are dominant in the ecoregion. Characteristic wildlife species include white-tailed deer, grey and red squirrel, and chipmunk. Bird species include the cardinal, wood thrush, screech owl, mourning dove, green heron, pileated and red-bellied woodpecker, and wild turkey. Agriculture is the predominant land use occupying 65% of the ecoregion, and major crops include corn, soybeans, tobacco, and tender fruit. The other dominant land use is urbanization, including residential, commercial, and industrial uses. The major communities include Toronto, Hamilton, St. Catharines, Niagara Falls, Windsor, Sarnia, London, Chatham, and Brantford. The population of the ecoregion is approximately 3 938 000.
This ecoregion is part of the Mixedwood Plains ecozone.