Wladimir Köppen in the context of "St. Petersburg"

A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, 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, 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 be semi-arid or arid. The cooler Dfb, Dwb, and Dsb subtypes are also known as hemiboreal 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 latitudes 40° N and 60° N, within the central and northeastern portions of North America, Europe, and Asia. Occasionally, they can also be found at higher elevations above other more temperate climate types. They are rare in the Southern 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.

The Köppen climate classification divides Earth's climates into five main climate groups, with each group being divided based on patterns of seasonal precipitation and temperature. The five main groups are A (tropical), B (arid), C (temperate), D (continental), and E (polar). Each group and subgroup is represented by a letter. All climates are assigned a main group (the first letter). All climates except for those in the E group are assigned a seasonal precipitation subgroup (the second letter). For example, Af indicates a tropical rainforest climate. The system assigns a temperature subgroup for all groups other than those in the A group, indicated by the third letter for climates in B, C, D, and the second letter for climates in E. Other examples include: Cfb indicating an oceanic climate with warm summers as indicated by the ending b., while Dwb indicates a semi-monsoonal continental climate, also with warm summers. Climates are classified based on specific criteria unique to each climate type.

The Köppen climate classification is the most widely used climate classification scheme. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notably in 1918 and 1936. Later, German climatologist Rudolf Geiger (1894–1981) introduced some changes to the classification system in 1954 and 1961, which is thus sometimes called the Köppen–Geiger climate classification.

Rudolf Oskar Robert Williams Geiger (/ˈɡaɪɡər/; German: [ˈɡaɪɡɐ]; 24 August 1894 – 22 January 1981) was a German meteorologist and climatologist. He was the son of Indologist Wilhelm Geiger and the brother of physicist Hans Geiger. He worked with Wladimir Köppen on climatology, hence the Köppen–Geiger climate classification.