plant and tree species. It is on the city's east side, near the university's Central Campus. Located across the Huron River just beyond the university's North Campus is the university's Matthaei Botanical Gardens, which contains 300 acres of gardens and a large tropical conservatory as well as a wildflower garden specializing in the vegetation of the southern Great Lakes Region.. The Kerrytown Shops, Main Street Business District, the State Street Business District, and the South University Business District are commercial areas in downtown Ann Arbor. Three commercial areas south of downtown include the areas near I-94 and Ann Arbor-Saline Road, Briarwood Mall, and the South Industrial area. Other commercial areas include the Arborland/Washtenaw Avenue and Packard Road merchants on the east side, the Plymouth Road area in the northeast, and the Westgate/West Stadium areas on the west side. Downtown contains a mix of 19th- and early-20th-century structures and modern-style buildings, as well as a farmers' market in the Kerrytown district. The city's commercial districts are composed mostly of two- to four-story structures, although downtown and the area near Briarwood Mall contain a small number of high-rise buildings. Ann Arbor's residential neighborhoods contain architectural styles ranging from classic 19th- and early 20th-century designs to ranch-style houses. Among these homes are a number of kit houses built in the early 20th century. Contemporary-style houses are farther from the downtown district. Surrounding the University of Michigan campus are houses and apartment complexes occupied primarily by student renters. Tower Plaza, a 26-story condominium building located between the University of Michigan campus and downtown, is the tallest building in Ann Arbor. The 19th-century buildings and streetscape of the Old West Side neighborhood have been preserved virtually intact; in 1972, the district was listed on the National Register of Historic Places, and it is further protected by city ordinances and a nonprofit preservation group. Climate Ann Arbor has a typically Midwestern humid continental climate (Köppen Dfa), which is influenced by the Great Lakes. There are four distinct seasons: winters are cold and snowy, with average highs around . Summers are warm to hot and humid, with average highs around and with slightly more precipitation. Spring and autumn are transitional between the two. The area experiences lake effect weather, primarily in the form of increased cloudiness during late fall and early winter. The monthly daily average temperature in July is , while the same figure for January