Warm-summer Humid Continental Climate (Dfb)

Warm-summer Humid Continental Climate (Dfb)


Dfb: D = Continental  f = Fully humid  b = Warm summer

humid continental climate is a climatic region typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers and freezing cold (sometimes severely cold in the northern areas) winters. Precipitation is usually distributed throughout the year but can have drier or dry seasons. 

Map Dfb, Deb, Deb


Humid continental climates: Warm summer sub-types Dfb, Dwb, and Dsb. Source Wikicommons. Authors: Peel, M. C., Finlayson, B. L., and McMahon, T. A. (University of Melbourne) 2011.

Also known as Hemiboreal climate, areas featuring this subtype of the continental climate have an average temperature in the warmest month below 22°C. Summer high temperatures in this zone typically average between 21–28°C during the daytime and the average temperatures in the coldest month are generally well or far below the −3°C isotherm. Frost-free periods typically last 3–5 months. Heat spells lasting over a week are rare.

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 about 42°N to 50°N latitude mostly east of 100°W, including parts of Southern Ontari, the southern half of Quebec & The Maritimes, and Newfoundland, as well as the northern United States from eastern North Dakota to Maine. However, it can be found as far north as 54°N, and further west in the Canadian Prairie Provinces and below 40°N in the high Appalachians. In Europe, this subtype reaches its most northerly latitude in Bodø at 67°N.

High-altitude locations such as Aspen, Colorado and Los Alamos, New Mexico in the western United States exhibit local Dfb climates. The south-central and southwestern Prairie Provinces also fits the criteria from a thermal profile, but because of semi-arid precipitation portions of it are grouped into the BSk category.

In Europe, it is found in much of Central Europe: Germany (in the east and southeast part of the country), Austria (generally below 2,297ft)), Poland, Czech Republic, Slovakia, Hungary (generally above 328 ft)), Croatia (mostly Slavonia region), in much of Eastern Europe: Ukraine (the whole country except the Black Sea coast), Belarus, Russia (mostly central part of European Russia), south and central parts of Scandinavia not bathed by the Atlantic Ocean or North Sea: Sweden (historical regions of Svealand and Götaland), Denmark, Finland (south end, including the three largest cities), Norway (most populated area), all Baltic States: Estonia, Latvia, Lithuania and also in parts of Romania (generally above 328ft)), Bosnia and Herzegovina, Turkey and in the Cairngorm Mountains of Scotland, (generally above 328ft)).

In the Southern Hemisphere, it exists in well-defined areas only in the Southern Alps of New Zealand, in the Snowy Mountains of Australia in Kiandra, New South Wales and the Andes Mountains of Argentina and Chile.

Flight safety and planning considerations

Low pressure systems bring low cloud, precipitation, strong winds and associated turbulence. Contaminated runways and strong cross-wind conditions increase risk of runway excursions. In-flight icing in frontal cloud can be a threat to aircraft safety, especially in the winter. High ambient temperatures in summer can have a significant and limiting impact on aircraft and human performance, as well as causing significant maintenance issues. Thunderstorms and wildfires are possible in summer. 

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