Ahumid continental climate is aclimatic region defined by Russo-GermanclimatologistWladimir Köppen in 1900,[1] typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers, and cold (sometimes severely cold in the northern areas) and snowy winters. Precipitation is usually distributed throughout the year, but often these regions do have dry seasons. The definition of this climate in terms of temperature is as follows: the mean temperature of the coldest month must be below 0 °C (32.0 °F) or −3 °C (26.6 °F) depending on the isotherm,[2] and there must be at least four months whose mean temperatures are at or above 10 °C (50 °F). In addition, the location in question must not besemi-arid orarid. The coolerDfb,Dwb, andDsb subtypes are also known ashemiboreal climates. Although amount of snowfall is not a factor used in defining the humid continental climate, snow during the winter in this type of climate is almost a guarantee, either intermittently throughout the winter months near the southern or coastal margins, or persistently throughout the winter months elsewhere in the climate zone.
Humid continental climates are generally found between latitudes40° N and60° N,[3] within the central and northeastern portions ofNorth America,Europe, andAsia. Occasionally, they can also be found at higher elevations above other more temperate climate types. They are rare in theSouthern Hemisphere, limited to isolated high altitude locations, due to the larger ocean area at that latitude, smaller land mass, and the consequent greater maritime moderation.
In the Northern Hemisphere, some of the humid continental climates, typically in aroundHokkaido,Sakhalin Island, northeastern mainlandEurope,Scandinavia,Nova Scotia, andNewfoundland are closer to the sea and heavily maritime-influenced and comparable tooceanic climates, with relatively cool summers, significant year-round precipitation (including high amounts of snow) and winters being just below the freezing mark (too cold for such a classification).[4]
More extreme and inland humid continental climates, sometimes known as "hyper-continental" climates, are found in northeastChina, southernSiberia,Mongolia,Kazakhstan, most of the southern interior ofCanada, and theUpper Midwest, where temperatures in the winter resemble those of adjacentsubarctic climates (with long, drier, generally very cold winters) but have longer and generally warmer summers (in occasional cases, hot summers). A more moderate variety, found in places likeHonshu, east-central China, theKorean Peninsula, parts ofEastern Europe, parts of southernOntario, much of theAmerican Midwest, and theNortheast US, the climate combines hotter summer maxima and greater humidity (similar to those found in adjacenthumid subtropical climates) and moderately cold winters and more intermittent snow cover (averaging somewhat below freezing, too cold for a more temperate classification), and is less extreme than the most inland hyper-continental variety.
The snowy city ofSapporo, Japan, has a humid continental climate (KöppenDfa).
Using theKöppen climate classification, a climate is classified as humid continental when the temperature of the coldest month is below 0 °C [32.0 °F] or −3 °C [26.6 °F] and there must be at least four months whose mean temperatures are at or above 10 °C (50 °F).[5] These temperatures were not arbitrary. In Europe, the −3 °C (27 °F) average temperatureisotherm (line of equal temperature) was near the southern extent of wintersnowpack. In the United States, it is more common to use the 0 °C [32.0 °F] isotherm instead. The 10 °C (50 °F) average temperature was found to be roughly the minimum temperature necessary for tree reproduction and growth.[6] Wide temperature ranges are common within this climate zone.[7]
Second letter in the classification symbol defines seasonal rainfall as follows:[5]
s: A dry summer—the driest month in the high-sun half of the year (April to September in the Northern Hemisphere, October to March in the Southern Hemisphere) has less than 30 millimetres (1.18 in)/40 millimetres (1.57 in) of rainfall and has exactly or less than1⁄3 the precipitation of the wettest month in the low-sun half of the year (October to March in the Northern Hemisphere, April to September in the Southern Hemisphere).
w: A dry winter—the driest month in the low-sun half of the year has exactly or less than one‑tenth of the precipitation found in the wettest month in the summer half of the year.
f: No dry season—does not meet either of the alternative specifications above; precipitation and humidity are often high year-round.
while the third letter denotes the extent of summer heat:[5]
a: Hot summer, warmest month averages at least 22 °C (71.6 °F),
b: Warm summer, warmest month averages below 22 °C (71.6 °F) but at least four months averages above 10 °C (50.0 °F).
Within North America, moisture within this climate regime is supplied by theGreat Lakes,Gulf of Mexico and adjacent western subtropicalAtlantic.[8]Precipitation is relatively well distributed year-round in many areas with this climate (f), while others may see a marked reduction in wintry precipitation,[6] which increases the chances of a wintertimedrought (w).[9]Snowfall occurs in all areas with a humid continental climate and in many such places is more common thanrain during the height of winter. In places with sufficient wintertime precipitation, the snow cover is often deep. Most summer rainfall occurs duringthunderstorms,[6] and in North America and Asia an occasionaltropical cyclone (or the remnants thereof). Thoughhumidity levels are often high in locations with humid continental climates, the "humid" designation means that the climate is not dry enough to be classified assemi-arid orarid.
By definition,forests thrive within this climate.Biomes within this climate regime include temperate woodlands, temperate grasslands, temperate deciduous or evergreen forests,[8] coniferous forests, and coniferous swamps.[10] Within wetter areas,maple,spruce,pine,fir, andoak can be found. Fall foliage is noted during the autumn of deciduous forests.[6]
In the poleward direction, these climates transition intosubarctic climates featuring short summers (and usually very cold winters) allowing onlyconifer trees. Moving equatorword, the hot-summer continental climates grade intohumid subtropical climates (chiefly in North America and Asia) while the warm-summer continental climates grade intooceanic climates (chiefly in Europe), both of which have milder winters where average temperatures stay above 0 °C (or -3 °C). Some continental climates with lower precipitation (chiefly in Central Asia and the Western United States) grade intosemi-arid climates with similar temperatures but low precipitation.
Regions with hot-summer humid continental climates
A hot summer version of a continental climate features an average temperature of at least 22 °C (71.6 °F) in its warmest month.[11] Since these regimes are restricted to the Northern Hemisphere, the warmest month is usually July or August. High temperatures during the warmest month tend to be in the high 20s to low 30s °C (80s °F), while average January afternoon temperatures are near or well below freezing. Frost-free periods typically last 4 to 7 months in this climate regime.[6]
WithinNorth America, this climate includes portions of the central and eastern United States from east of100°W to south of about the44°N to theAtlantic. Precipitation increases further eastward in this zone and is less seasonally uniform in the west. The western states of the westernUnited States (namelyMontana,Wyoming, parts of southernIdaho, most ofLincoln County inEastern Washington, parts ofColorado, parts ofUtah, isolated parts of northernNew Mexico, westernNebraska, and parts of westernNorth andSouth Dakota) have thermal regimes which fit theDfa climate type, but are quite dry, and are generally grouped with the steppe (BSk) climates.
In the Eastern Hemisphere, this climate regime is found within interiorEurasia and east-central Asia. Within Europe, theDfa climate type is present near theBlack Sea in southernUkraine, theSouthern Federal District ofRussia, southernMoldova,Serbia, parts of southernRomania, andBulgaria,[12][13] but tends to be drier and can be even semi-arid in these places. In East Asia, this climate exhibits amonsoonal tendency with much higher precipitation in summer than in winter, and due to the effects of the strongSiberian High much colder winter temperatures than similar latitudes around the world, however with lower snowfall, the exception being western Japan with its heavy snowfall.
Tōhoku on the western coast of Japan also has a climate with Köppen classificationDfa, but is wetter even than that part of North America with this climate type. A variant which has dry winters and hence relatively lower snowfall with monsoonal type summer rainfall is to be found in northernChina includingManchuria and parts ofNorth China, far East ofRussia, and over much of theKorean Peninsula; it has the Köppen classificationDwa. Much ofcentral Asia,northwestern China, and southernMongolia has a thermal regime similar to that of theDfa climate type, but these regions receive so little precipitation that they are more often classified as steppes (BSk) or deserts (BWk).
Dsa climates are rare; they are generally restricted to elevated areas adjacent to mid-latitudeMediterranean climate regions with aCsa climate well inland to ensure hot summers and cold winters. They are generally found in the highly elevated areas of south-eastern Turkey (Hakkâri), north-western Iran, northern Iraq, parts ofCentral Asia, parts of theHigh Atlas mountain range in central Morocco and very small parts of theIntermountain West in the United States.
This climate zone does not exist at all in the Southern Hemisphere, where the continents either do not penetrate low enough in latitude ortaper too much to have any place that gets the combination of snowy winters and hot summers. Marine influences are very strong around 40°S and such precludeDfa,Dwa, andDsa climates from existing in the southern hemisphere.
Regions with warm-summer humid continental climates
Also known ashemiboreal climate, areas featuring this subtype of the continental climate have an average temperature in the warmest month below 22 °C (72 °F). Summer high temperatures in this zone typically average between 21–28 °C (70–82 °F) during the daytime and the average temperatures in the coldest month are generally well or far below the −3 °C (27 °F) (or 0 °C (32.0 °F)) isotherm. Frost-free periods typically last 3–5 months. Heat spells lasting over a week are rare.[6]
The warm summer version of the humid continental climate covers a much larger area than the hot subtype. In North America, the climate zone covers from about42°N to50°N latitude mostly east of100°W, including parts ofSouthern Ontario, the southern half ofQuebec,The Maritimes, andNewfoundland, as well as the northern United States from easternNorth Dakota east toMaine. However, it can be found as far north as54°N, and further west in the CanadianPrairie Provinces[20] and below40°N in the highAppalachians. In Europe, this subtype reaches its most northerly latitude inBodø at the67°N.[21]
High-altitude locations such asFlagstaff, Arizona,Aspen, Colorado andLos Alamos, New Mexico in the western United States exhibit localDfb climates. The south-central and southwesternPrairie Provinces also fits theDfb criteria from a thermal profile, but because of semi-arid precipitation portions of it are grouped into theBSk category.[22]
In Asia, this climate type is found in northernKazakhstan, southernSiberia, parts ofMongolia, northernChina, and highland elevations in theKoreas. Like its hot-summer counterpart, these climates are typically dry in the winter and bitterly cold due to theSiberian High (often with winter temperatures comparable to their nearbysubarctic climates), while summers are warm and long enough to avoid classification as a subarctic climate.
Since climate regimes tend to be dominated by vegetation of one region with relatively homogenous ecology, those that projectclimate change remap their results in the form of climate regimes as an alternative way to explain expected changes.[1]
^"Station: Chicago Midway AP 3SW, IL".U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991–2020). National Climatic Data Center. RetrievedMay 14, 2021.
^Williams, B. W.; Proctor, H. C.; Clayton, T. (2011). "Range Extension of the Northern Crayfish, Orconectes Virilis (decapoda, Cambaridae), in the Western Prairie Provinces of Canada".Crustaceana.84 (4):451–460.doi:10.1163/001121611X563995.JSTOR23034238.
