An oceanic climate, also known as a marine climate or maritime climate, is the
Köppen classification of climate typical of west coasts in higher middle latitudes of continents, and generally features mild summers (relative to their latitude) and mild
winters, with a relatively narrow annual
temperature range and few extremes of temperature, with the exception for transitional areas to
subarctic and highland climates. Oceanic climates are defined as having a monthly mean temperature below 22 °C (72 °F) in the warmest month, and above 0 °C (32 °F) (or −3 °C (27 °F)) in the coldest month.
Oceanic climates can have considerable storm activity as they are located in the belt of the stormy westerlies. Many oceanic climates have frequent cloudy or overcast conditions due to the near constant storms and lows tracking over or near them. The annual range of temperatures is smaller than typical climates at these latitudes due to the constant stable marine air masses that pass through oceanic climates, which lack both very warm and very cool fronts.
Locations with oceanic climates tend to feature cloudy conditions with precipitation, though it can experience clear, sunny days. London is an example of an oceanic climate. It experiences reliable and constant precipitation throughout the entire year. Despite this, thunderstorms are quite rare since hot and cold air masses meet infrequently in the region.
In most areas with an oceanic climate, precipitation comes in the form of rain for the majority of the year. However, some areas with this climate see some snowfall annually during winter. Most oceanic climate zones, or at least a part of them, experience at least one snowfall per year. In the poleward locations of the oceanic climate zone ("subpolar oceanic climates," described in greater detail below), snowfall is more frequent and commonplace.
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 0 °C (32 °F) (or −3 °C (27 °F)) or higher in the coldest month, compared to continental climates where the coldest month has a mean temperature of below 0 °C (32 °F) (or −3 °C (27 °F)). Summers are cool, with the warmest month having a mean temperature below 22 °C (72 °F). Poleward of the latter is a zone of the aforementioned subpolar oceanic climate (Köppen Cfc), with long but relatively mild (for their latitude) winters and cool and short summers (average temperatures of at least 10 °C (50 °F) for one to three months). Examples of this climate include parts of coastal
Scottish Highlands, the mountains of
Vancouver Island, and
Haida Gwaii in
Canada, in the
Northern Hemisphere and extreme southern
Argentina in the
Southern Hemisphere (examples include
Punta Arenas), the
Tasmanian Central Highlands, and parts of
Oceanic climates are not necessarily always found in coastal locations on the aforementioned parallels; however, in most cases oceanic climates parallel higher middle latitude oceans. The polar
jet stream, which moves in a west to east direction across the middle latitudes, advances low pressure systems, storms, and fronts. In coastal areas of the higher middle latitudes (45–60° latitude), the prevailing onshore flow creates the basic structure of most oceanic climates. Oceanic climates are a product and reflection of the ocean adjacent to them. In the fall, winter, and early spring, when the polar jet stream is most active, the frequent passing of marine weather systems creates the frequent fog, cloudy skies, and light drizzle often associated with oceanic climates. In summer, high pressure often pushes the prevailing westerlies north of many oceanic climates, often creating a drier summer climate (for example in the
Northwest coast of
America, bathed by the
The North Atlantic
Gulf Stream, a tropical oceanic current that passes north of the Caribbean and up the East Coast of the United States to
North Carolina, then heads east-northeast to the Azores, is thought to greatly modify the climate of Northwest Europe. As a result of the Gulf Stream, west-coast areas located in high latitudes like Ireland, the UK, and Norway have much milder winters (for their latitude) than would otherwise be the case. The lowland attributes of western Europe also help drive marine air masses into continental areas, enabling cities such as
Vienna to have maritime climates in spite of being located well inland from the ocean.
The oceanic climate exists in an arc spreading across the north-western coast of North America from the Alaskan panhandle to northern California, in general the coastal areas of the
Pacific Northwest. It includes the western parts of
Alaskan panhandle, western portions of
British Columbia, and north-western
California. In addition, some east coast areas such as some higher elevations along the southern
Appalachian Mountains as well as
Martha's Vineyard, and
Nantucket have a similar climate. The oceanic climate is found in isolated pockets in eastern Mexico. The White Mountains of Northern Arizona have an oceanic cfb climate. An extensive area of oceanic climates distinguishes the coastal regions of southern
Chile and extends into bordering
The only noteworthy area of Maritime Climate at or near sea-level within Africa is in South Africa from
Mossel Bay on the
Western Cape coast to
Plettenberg Bay, with additional pockets of this climate inland of the
Eastern Cape and
KwaZulu-Natal coast. It is usually warm most of the year with no pronounced rainy season, but slightly more rain in autumn and spring. The
Tristan da Cunha archipelago in the South Atlantic also has an oceanic climate.
The oceanic climate is prevalent in the more southerly parts of
Oceania. A mild maritime climate is in existence in New Zealand. It occurs in a few areas of Australia, namely in the southeast, although average high temperatures during summers there tend to be higher and the summers drier than is typical of oceanic climates, with summer maxima sometimes exceeding 40 °C (104 °F),Tasmania,
Victoria and southeastern
New South Wales. It can also be found along the western areas of the south coast of
Western Australia, parts with
steppe-like (BSk) or even
desert-like (BWk) scarcity of precipitation.
This climate is found on the Asian mainland in mountainous areas of the tropics, such as the foothills of the
The subtropical highland variety of the oceanic climate exists in elevated portions of the world that are within either the tropics or subtropics, though it is typically found in mountainous locations in some tropical countries. Despite the latitude, the higher altitudes of these regions mean that the climate tends to share characteristics with oceanic climates, though it can experience noticeably drier weather during the lower-sun "winter" season. In locations outside the tropics, other than the drying trend in the winter, subtropical highland climates tend to be essentially identical to an oceanic climate, with mild summers and noticeably cooler winters, plus, in some instances, some snowfall. In the tropics, a subtropical highland climate tends to feature spring-like weather year-round. Temperatures there remain relatively constant throughout the year and snowfall is seldom seen.
Areas with this climate feature monthly averages below 22 °C (72 °F) but above −3 °C (27 °F) (or 0 °C (32 °F) using American standards). At least one month's average temperature is below 18 °C (64 °F). Without their
elevation, many of these regions would likely feature either
humid subtropical climates.
Temperate oceanic climates, also known as "marine mild winter" climates (themselves) or simply oceanic climates, are found either at
middle latitudes. They are often found on or near the west coast of continents; hence another name for Cfb, i.e. "marine west coast" climates. In addition to moderate temperatures year-round, one of the characteristics is the absence of dry season. Except for the western part of
Europe, this type of climate is confined to narrow ranges of occurrences mainly in the low latitudes and to the east of the continents where it appears in the form of "arch" accompanying elevations, as
plateaus in the
subtropics. It arises in both hemispheres between 35° and 60°: at low altitudes between
humid continental climates and
subartic, although the latter usually are also grouped in marine climates limited by the east border of the ocean basins. The west winds ease temperatures, even if there is a partial participation of warm
sea currents. With the air coming from the ocean predominates the cloudy weather with constant precipitation even in the colder months and the temperature is strongly enlivened. Depending on the continent its distribution is greater due to the absence of
mountains in the north and south direction. Without a deep layer of snow and sufficient moisture the entire year the
vegetation is usually always seeing under normal conditions. The vegetation is temperate with the presence of
cedar. As well as
In the hottest month the average temperature is below 22 °C, but it's in minimum four months with temperatures above 10 °C. The average temperature of the coldest month must be -3 °C or 0 °C (
eastern United States) to avoid falling into a continental climate in interior areas or of less influence of the adjacent ocean. The average temperature variations in the year are between 10 and 15 °C with average annual temperatures between 7 °C and 13 °C if it is not a
Rain values can vary from 50 cm to 10 times the minimum value by the
orographic factor. It is dominated by
frontal cyclones, where there are places where rainy days exceed 150 times a year. But contrary to popular belief, there are few
storms and yes they at occurrences of the precipitation are in constant quantities. Another feature is the very reduced visibility in the winter.
Areas with subpolar oceanic climates feature an oceanic climate but are usually located closer to polar regions. As a result of their location, these regions tend to be on the cool end of oceanic climates. Snowfall tends to be more common here than in other oceanic climates. Subpolar oceanic climates are less prone to temperature extremes than
subarctic climates or
continental climates, featuring milder winters than these climates. Subpolar oceanic climates feature only one to three months of average monthly temperatures that are at least 10 °C (50 °F). As with oceanic climates, none of its average monthly temperatures fall below -3.0 °C (26.6 °F) or 0 °C depending on the isotherm used. Typically, these areas in the warmest month experience daytime maximum temperatures below 17 °C (63 °F), while the coldest month features highs near or slightly above freezing and lows just below freezing. It typically carries a Cfc designation, though very small areas in
Sichuan and parts of
Bolivia have summers sufficiently short to be Cwc with fewer than four months over 10 °C (50 °F).El Alto, Bolivia, is one the few confirmed towns that features this rare variation of the subpolar oceanic climate. The more warm summer/cool winter variation of this climate type is also sometimes known as a "continental maritime climate" as it often has more in common with continental climates than with tundra climates, a great example of this would be
Norway, which like nearby
Tromso has moderately cold, snowy winters and mild to warm summers making this somewhat of a cool summer version of a four-season climate. Mountain summits of
South Island of New Zealand,
Vancouver Island of
Tierra del Fuego, and
Patagonia expirence the sub polar variety, meaning that they have moderate to cool summers, and snowy winters.
This variant of an oceanic climate is found in parts of coastal
Faroe Islands, parts of
Scotland, northwestern coastal areas of
Norway such as
Lofoten and reaching to 70°N on some islands, uplands near the coast of southwestern Norway, the
Aleutian Islands of
Alaska and northern parts of the
Alaskan Panhandle, the far south of
Argentina, and a few highland areas of
Tasmania, and the
Southern Alps. This type of climate is even found in the very remote parts of the Papuan Highlands in Indonesia. The classification used for this regime is Cfc. In the most marine of those areas affected by this regime, temperatures above 20 °C (68 °F) are extreme weather events, even in the midst of summer. Temperatures above 30 °C (86 °F) have been recorded on rare occasions in some areas of this climate, and in winter temperatures down to −20 °C (−4 °F) have seldom been recorded in some areas.
^Tapper, Andrew; Tapper, Nigel (1996). Gray, Kathleen, ed. The weather and climate of Australia and New Zealand (First ed.). Melbourne, Australia: Oxford University Press. p. 300.