Humid subtropical climate

Humid subtropical climates are characterized by hot, humid summers and cool to mild winters. Rainfall is distributed fairly evenly throughout the year. Winter rainfall—and sometimes snowfall—is associated with large storm systems that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and an occasional tropical storm or hurricane. Humid subtropical climates lie on the southeast side of continents, roughly between 24 degrees and 37 degrees latitude. The main temperature range in this climate, considering normal annual extremes, is 10° F to 110 °F (-13°C to 38°C), though this range may greatly depending on the exact location.

Humid subtropical climates in Asia

Humid subtropical climates are found on the east-central coast of China, as well as in the majority of South Korea and lowland Japan. However, the distinction is difficult to make in Japan, whose temperatures can either be considered subtropical or humid continental, depending on latitude.

Humid subtropical climates in North America

In North America, humid subtropical climates are almost exclusively the domain of the American South, including part or most of eastern Texas, Louisiana, most of Arkansas, Mississippi, much of Tennessee, much of Kentucky, Alabama, North Carolina, Georgia, Virginia, Delaware, most of Florida, South Carolina, eastern portions of Maryland, and southeastern Pennsylvania. The exceptions in those states lie in the higher elevations, particularly in the Appalachian Mountains (such as Charleston, WV and Roanoke, VA), where a humid continental climate exists due to the higher elevation and colder overall temperatures (especially in the winter).

Major cities in this climate zone include Atlanta, Houston, Dallas, New Orleans, Nashville, Greenville, SC, Charlotte, Raleigh, Tampa, Little Rock, Tampa, and possibly Miami, Louisville, Washington, DC, Baltimore, Philadelphia, and Wilmington, DE. Some of these cities, such as Miami, are of a warmer variety, and others, such as Baltimore, are of a colder variety.

Characteristics and variants

The southernmost limits of this climate are around Miami and southern coastal Texas, and areas further south have a true tropical climate with a very warm weather year round and minimal temperature differences between seasons. The northernmost limits of the humid subtropical climate are often considered to be around Philadelphia, southwest to Washington, DC and the edge of the Blue Ridge west to Louisville, Kentucky then roughly along the Ohio River. Areas further north, inland, and higher in elevation have a humid continental climate with cold and harsh winters.

Snowfall varies greatly in this climate zone. In areas around Florida and the Gulf Coast, snow is very rare. In southern cities farther north, such as Atlanta, Little Rock, Dallas, Nashville, Charlotte, Raleigh, and Norfolk, snowfall is sporadic and uncommon, but not unheard of. In the northern limits of this climate zone, in cities like Baltimore and Louisville, snow is more common and it occurs every year. Significant snowfalls are also relatively common in those locations.

Precipitation is plentiful in the humid subtropical climate zone. Although most areas tend to have precipitation spread evenly throughout the year, a somewhat monsoon-like pattern is seen in parts of the Southeast (in locales such as Augusta, Georgia and Columbia, South Carolina), which experience an extremely dry (by humid subtropical standards) and warm spring, followed immediately by a hot and humid summer. In addition, areas in Texas that are slightly inland from the Gulf of Mexico, such as Austin, generally see a peak of precipitation in the spring, and a deep, drought-like nadir in mid-summer.