Geography of Louisville, Kentucky

Louisville is a city in Jefferson County, in the U. S. state of Kentucky. It is located at the Falls of the Ohio River. Louisville is located at According to the U. S. Census Bureau, Louisville Metro (in 2015 measurements for Jefferson County) has a total area of 397.68 square miles (1,030 km2), of which 380.46 square miles (985 km2) is land and 17.23 square miles (45 km2) (4.33%) is covered by water.

Although the soils and underlying rocks officially put Louisville in the outer Bluegrass region, the city's landscape is better described as being in a very wide part of the Ohio River flood plain. Louisville's part of the valley is located between two plateaus, the karst plateau of Southern Indiana and the Bluegrass plateau of Kentucky, both with an elevation of around 900 feet. Elevations drop off the Indiana plateau very sharply via the Muldraugh Escarpment, whereas the rise in elevation up to the Bluegrass plateau is more gradual. The flood plain is much longer north to south than it is east to west. For example, within several miles of downtown, the Highlands sitting at 540 feet is out of the thousand year flood plain, whereas areas 10 miles from downtown such as Fairdale and Okolona (both between seven and 11 miles from the river) have the same elevation as downtown Louisville. Most areas in the east end have an elevation from 600 to 700 feet, which, with the typically eastbound winds, trap in heat and pollutants. Areas along and west of the south fork of Beargrass Creek (and more generally, I 65) are located where the Ohio River once ran, so the land here is very flat and is composed of harder rocks. Prior to urbanization much of this area was composed of wetlands, and early roads through these were made of wooden planks. This history is occasionally still readily evident in street names, for example, the spoke road Poplar Level, whose name describes its original construction on planks of poplar. 3rd Street was formerly called Central Plank Road for the same reason. As an industry, namely Standiford Field airport, moved into the area in the 1950s most creeks through the area were rerouted into ditches to alleviate the area's poor drainage and constant flooding. Areas east of I 65 were generally not in the flood plain and thus are mostly gentle rolling hills composed of soft loess soils, hence the reason roads here (such as Eastern Parkway) are very prone to potholes. The southern quarter of Jefferson County is in the scenic and rugged Knobs region. This is the only part of Jefferson County to not have experienced any urbanization and is today almost entirely parkland for the Jefferson Memorial Forest. The eastern third is in the Eden Shale Hills section of the Bluegrass region and has also experienced less urbanization than the flood plain, although that is starting to change.

The Louisville Jefferson County, KY IN Metropolitan Statistical Area (MSA), the 43rd largest in the United States, includes the Kentucky counties of Jefferson (coterminous with Louisville Metro), Bullitt, Henry, Meade, Nelson, Oldham, Shelby, Spencer and Trimble. The southern Indiana counties Clark, Floyd, Harrison and Washington are also included in the Louisville MSA. This MSA is included in the Louisville Elizabethtown Scottsburg, KY IN Combined Statistical Area (CSA), which also includes the Elizabethtown, KY MSA (composed of Hardin and LaRue Counties) as well as the Scottsburg, IN Micropolitan Statistical Area. Louisville's Metro Area was expanded more than any other in the country during a March 2003 overhaul of U. S. Metropolitan Area statistics by the federal government. In the 2000 census, even very fast growing counties such as Spencer County weren't included. The Metro Area's ranking rose from 49th to 42nd, and the added Combined Statistical Area measured the area as the nation's 31st largest. The total Metro area population also increased dramatically from just over 1 million to nearly 1.4 for the CSA. Seventeen percent of the state's population lives in Jefferson County and 25% live in counties in the Louisville CSA, and also Jefferson County has two and a half times more people than Kentucky's second most populous county, Fayette County. Twelve of the 15 buildings in Kentucky over 300 feet are located in Downtown Louisville. Almost 40% of the population growth in Kentucky are in Louisville's CSA counties.

Louisville has a humid subtropical climate (Köppen Cfa), typical of the Upper South, with four distinct seasons and is located in USDA hardiness zones 6b and 7a. Spring like conditions typically begin in mid to late March, summer from mid to late May to late September, with fall in the October–November period. Seasonal extremes in both temperature and precipitation are not uncommon during early spring and late fall; severe weather is not uncommon, with occasional tornado outbreaks in the region. Winter typically brings a mix of rain, sleet, and snow, with occasional heavy snowfall and icing. Louisville averages 5.8 days with low temperatures dipping to , while readings of or below occur on average every several years, the last occurrence being January 7, 2014; the average window for freezing temperatures is October 31 thru April 6, allowing a growing season of 207 days. The highest recorded temperature was , which last occurred on July 14, 1936, and the lowest recorded temperature was on January 19, 1994. The record high daily minimum was on August 19, 1936, while the record low daily maximum was on January 12, 1918; the only other sub daily maximum occurred on January 5, 1884. In 2012, Louisville had the fourth hottest summer on record, with the temperature rising up to in July and the June all time monthly record high temperature being broken on two consecutive days. Air pollution is trapped in Louisville's Ohio River Valley location. The city is ranked by Environmental Defense as America's 38th worst city for air quality. Louisville's lowest solar noon is 28.4 degrees with the shortest daylength being 9 hours and 30 seconds, both occurring from December 17–26. The city's highest solar noon is 75.2 degrees with the longest daylength being 14 hours and 39 seconds, both occurring from June 17–25. The city's March and September equinox occurs at 50.5 degrees.