Köppen's A climates exist near the equator, mostly between 15° N and S latitudes. These regions receive consistent and ample solar radiation, leading to high temperatures (generally above 18°C or 64°F) without distinct seasons. Day-night temperature variations are often greater than monthly differences. While "winter" and "summer" aren't well-defined, wet and dry seasons provide an annual rhythm. Köppen outlines three A climates:

Wet equatorial (Af)

Tropical monsoon and trade-wind coastal (Am)

Tropical wet-dry (Aw)

A's climates are influenced by trade winds, the intertropical convergence zone (ITCZ), and the Asian monsoon.

Arid and semiarid climates cover about 25% of Earth's land, primarily between 50° N and 50° S latitudes, with a focus on the 15–30° latitude range in both hemispheres. They experience low rainfall, erratic yearly precipitation, low humidity, high evaporation rates (when water is present), clear skies, and intense sunlight. Köppen identifies three B climates:

Tropical and subtropical desert (BWh, part of BWk)

Mid-latitude steppe and desert (BSh)

Tropical and subtropical steppe (BSk, part of BWk)

Within middle and high latitudes (mainly 25° to 70° N and S), Köppen categorizes climates as C and D types. These regions sit under upper-level westerlies, and their climatic characteristics arise from seasonal shifts and strengths of these winds. In summer, the polar front and jet stream move northward, allowing tropical air to extend to high latitudes. Winter sees the opposite, with polar air affecting even subtropical areas. This air mass mixture causes gradual temperature changes across the belt, most notably in winter. Frontal systems, often in traveling cyclones beneath the jet stream, generate precipitation through convergence and uplift. Convection in tropical areas and uplift by mountains also contribute. Monsoons and subtropical anticyclones modify this pattern. Köppen identifies six C climates and eight D climates:

Humid subtropical (Cfa, Cwa)

Mediterranean (Csa, Csb)

Marine west coast (Cfb, Cfc)

Humid continental (Dfa, Dfb, Dwa, Dwb)

Continental subarctic (Dfc, Dfd, Dwc, Dwd)

Köppen's E climates are influenced by polar and arctic air masses at latitudes of 60° N and S or higher. They feature low temperatures and precipitation, with diverse subtypes. Additionally, type H climate covers highland areas not fitting other types. Although not initially in Köppen's system, later versions include it. Köppen's two E climates and the H climate are:

Tundra (ET)

Snow and ice (EF)

Highland (H)