Humid Continental Climate - Dfa/Dwa/Dsa: Hot (or Very Warm) Summer Subtype

Dfa/Dwa/Dsa: Hot (or Very Warm) Summer Subtype

A hot (or very warm) version of a continental climate features an average temperature of at least 22 °C (71.6 °F) in its warmest month. The warmest month is usually July, though in some cases, it can be August. In this region, July afternoon temperatures average up to 32 °C (90 °F), while the January mean temperature can be far below −3 °C (26.6 °F). In Europe, it is found in areas largely inland in Romania, Moldova, Ukraine, in the Pannonian Basin in parts of Hungary, Croatia and Serbia and in the Don River estuary of Russia. In Asia, around the Caspian Sea in Russia, Kazakhstan, in parts of Iran, Turkey and parts of Kashmir in India. It covers a great swath of Northeast China, almost all of North Korea, most of South Korea and much of northern Japan (including most of Hokkaido) as well as various central areas. In East Asia, this climate exhibits a monsoonal tendency with much higher precipitation in summer than in winter, and due the effects of the strong Siberian High much colder winter temperatures than similar latitudes around the world, however with lower snowfall, the exception being western Japan with its heavy snowfall. Within North America, it includes parts of southern New England and the Middle Atlantic states, much of the Midwestern United States, and small parts of Southern Ontario, Canada, from the Atlantic to the 100th meridian, and in the general range of between 39 °N to 44 °N latitude (with a larger north-south spread in the western portion due to the lack of maritime influences); precipitation increases further eastward in this zone and is less seasonally uniform in the west.

The 0 °C (32 °F) isotherm (freeze line) and the −3 °C (27 °F) isotherm (persistent-snow line) are often both argued as the statistical dividing line between the humid continental climate dominating areas to the north and west and the humid subtropical climate dominating areas to the south and southwest. The Köppen climate classification, the most popular climate classification, uses −3 °C (27 °F) as its lower threshold criterion; however, many climatologists in the U.S. prefer to use 0 °C (32 °F) as the standard because they feel it better reflects consistency in regional floristic character (i.e. forest composition/type).

The western states of the central United States (namely Montana, Wyoming, parts of southern Idaho, parts of Colorado, western Nebraska, and parts of western North and South Dakota) have thermal regimes which fit the Dfa climate type, but are quite dry, and are generally grouped with the steppe (BSk) climates.

Outside of North America the Dfa climate type is present near the Black Sea in southern Ukraine, the Southern Federal District of Russia, southern Moldova, and parts of southern and western Romania, but tends to be drier and can be even semi-arid, in these places. Tohoku in Japan between Tokyo and Hokkaidō also has a climate with Köppen classification Dfa, but is wetter even than that part of North America with this climate type. A variant which has dry winters and hence much lower snowfall with monsoonal type summer rainfall is to be found in north-eastern China including coastal regions of the Yellow Sea and over much of the Korean Peninsula; it has the Köppen classification Dwa. Much of central Asia, northwestern China, and southern Mongolia have a thermal regime similar to that of the Dfa climate type, but these regions receive so little precipitation that they are more often classified as steppes (BSk) or deserts (BWk).

It appears nowhere within the Southern Hemisphere, which has no large landmasses so situated in the middle latitudes that allow the combination of hot summers and at least one month of sub-freezing temperatures.