An oceanic climate, also known as a marine climate, is the temperate climate sub-type in Köppen classification represented as Cfb, typical of west coasts in higher middle latitudes of continents, generally featuring cool summers and mild winters (for their latitude), with a relatively narrow annual temperature range and few extremes of temperature. Oceanic climates can be found in both hemispheres generally between 45 and 63 latitude, most notably in northwestern Europe, northwestern America, as well as New Zealand. Other varieties of climates usually classified together with these include subtropical highland climates, represented as Cwb or Cfb, and subpolar oceanic or cold subtropical highland climates, represented as Cfc or Cwc. Subtropical highland climates occur in some mountainous parts of the subtropics or tropics, some of which have monsoon influence, while their cold variants and subpolar oceanic climates occur near polar or tundra regions.
Locations with oceanic climates tend to feature frequent cloudy conditions with precipitation, low hanging clouds, and frequent fronts and storms. Thunderstorms are normally few, since strong daytime heating and hot and cold air masses meet infrequently in the regions, but are more common in subtropical highland climates where these air masses meet more frequently due to the influence of hotter weather in the subtropics or tropics, especially in monsoon-influenced climates. In most areas with an oceanic climate, precipitation comes in the form of rain for the majority of the year. Most oceanic climate zones, or at least a part of them, however, experience at least one snowfall per year. Snowfall is more frequent and commonplace in the subpolar oceanic climates due to the colder weather in those locations.
Overall temperature characteristics of the oceanic climates feature cool temperatures and infrequent extremes of temperature. In the Köppen climate classification, oceanic climates have a mean temperature of or higher (or or higher) in the coldest month, compared to continental climates where the coldest month has a mean temperature of below (or ) in the coldest month.