Oceanic climate
An oceanic climate, also known as a marine climate or maritime 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 warm summers and cool to mild winters, with a relatively narrow annual temperature range and few extremes of temperature. Oceanic climates can be found in both hemispheres generally between 40 and 60 degrees latitude, with subpolar versions extending to 70 degrees latitude in some coastal areas. 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.
Precipitation
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, 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.Temperature
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 in the coldest month, compared to continental climates where the coldest month has a mean temperature of below . Summers are warm but not hot, with the warmest month having a mean temperature below.Poleward of the latter is a subtype of it, the subpolar oceanic climate, with long but relatively mild winters, and cool and short summers with average temperatures of at least for one to three months. Examples in the Northern Hemisphere include parts of coastal Iceland, the coast of Norway north of Bodø, the mountains of Scotland, parts of Shetland, and the British Columbian coast in Canada. In the Southern Hemisphere, examples include extreme southern Chile and Argentina, the Falkland Islands, parts of southeastern Australia, and much of New Zealand.
Cause
Oceanic climates are not necessarily 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, the prevailing onshore flow creates the basic structure of most oceanic climates. Oceanic climates are a product and reflection of the cool ocean adjacent to them. In the autumn, 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. They are typically found poleward of Mediterranean climates, except in Australia where they are poleward of both such climates and humid subtropical climates due to the shape of the continent. Only in Europe do they penetrate far inland, where they eventually transition into warm-summer humid continental climates; in other continents, they are blocked by a large mountain range or limited by nearby oceans.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 Grand Banks of Newfoundland, is thought to greatly modify the climate of northwest Europe. As a result of the North Atlantic Current, west coast areas located in high latitudes like Ireland, the UK, and Norway have much milder winters 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 Dresden, Prague, and Vienna to have maritime climates in spite of being located well inland from the ocean.
Locations
Europe
Oceanic climates in Europe occupy a large stretch of land, from Norway's Atlantic coast, the British Isles and southeast to some parts of northern Turkey.Western Europe is almost exclusively oceanic between 45°N to 54.913°N; including most of France, nearly all of Belgium, the Netherlands, Austria, most of Luxembourg, most of Denmark, western Germany, northwestern Switzerland, south coast and western areas of Norway north to Skrova and extreme southern Sweden.
While most of Southern Europe is climatically Mediterranean, some parts of Southern Europe also have oceanic climates. However, these instances of the climate are highly variable, and often somewhat anomalous. The north coast of Spain, the western Azores off the coast of Portugal are too wet in summer to be Mediterranean, and too mild in summer to be humid subtropical, though they often have winter means above, unusual for European oceanic climates.
Another anomalous case can be found in northwestern Turkey, including northern Istanbul. These places are, in a strict air-mass sense, not oceanic: they are affected by southerlies directly from the Mediterranean, and polar intrusions from Siberia. Yet their position near the Black Sea makes them too wet in summer to be Mediterranean, too mild during winter to be humid continental, and not hot enough in summer to be humid subtropical; therefore Köppen classifies them as oceanic. Despite their anomalous position, however, their temperatures, around in winter and in summer, are not wholly atypical for European oceanic climates.
Some Eastern European regions such as the north of Croatia and Serbia and some parts of the Czech Republic, also have oceanic climates; these are generally near the boundary for being humid continental.
The line between oceanic and continental climates in Europe runs in a generally northwest to southeast direction. For example, western Germany is more impacted by milder Atlantic air masses than eastern Germany. Thus, winters across Europe become colder to the east, and summers become hotter. The line between oceanic Europe and Mediterranean Europe normally runs west to east and is related to changes in precipitation patterns and differences to seasonal temperatures; although intrusions of polar air, remnants of marine air-masses, and higher summer precipitation can create oceanic climates in Eastern Europe and transcontinental regions as far south as 40°N.
The Americas
The oceanic climate exists in an arc spreading across the northwestern coast of North America from the Alaskan panhandle to northern Washington. In addition, some east coast areas such as Block Island, Cape Cod, Martha's Vineyard, and Nantucket have a similar climate. And in the highlands of Central and South America with the variant Cfb. An extensive area of oceanic climates distinguishes the coastal regions of southern Chile and extends into bordering Argentina.Africa
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.Asia and Oceania
Although oceanic climate is rare in Asia, subtropical highland climates and cold subtropical highland climates can be found in parts of Southwestern China, and the Himalayan regions of the northern Indian subcontinent.The oceanic climate is prevalent in the more southerly parts of Oceania. A mild maritime climate is in existence in New Zealand. In Australia, the climate is found in Tasmania, southern half of Victoria and southeastern New South Wales.
The hinterland of the northern coast of Turkey, features this climate. Additionally, parts of the northeastern coast of Honshu, such as Mutsu, Aomori in Japan, feature this climate, which is rare in Asia due to the lack of a west coast in the middle latitudes.
Indian Ocean
and Île Saint-Paul, both part of the French Southern and Antarctic Lands, are located in the subtropics and have an oceanic climate.Varieties
Marine west coast (Cfb)
Temperate oceanic climates, also known as "marine mild winter" climates 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, "marine west coast climates". In addition to moderate temperatures year-round, one of the characteristics is the absence of a dry season. Except for Europe, this type of climate is confined to narrow bands of territory, largely in mid or high latitudes, although it can appear in elevated areas of continental terrain in low latitudes, e.g. plateaus in the subtropics. It exists in both hemispheres between 35° and 60°: at low altitudes between Mediterranean, humid continental, and subarctic climates.Western sea breezes ease temperatures and moderates the winter, especially if warm sea currents are present, and cause cloudy weather to predominate. Precipitation is constant, especially in colder months, when temperatures are warmer than elsewhere at comparable latitudes. This climate can occur farther inland if no mountain ranges are present or nearby. As this climate causes sufficient moisture year-round without permitting deep snow cover, vegetation typically prospers in this climate. Deciduous trees are predominant in this climate region. However, conifers such as spruce, pine, and cedar are also common in few areas, and fruits such as apples, pears, and grapes can often be cultivated here.
In the hottest month, the average temperature is below, and at least four months feature average temperatures higher than. The average temperature of the coldest month must not be colder than, or the climate will be classified as continental. The average temperature variations in the year are between, with average annual temperatures between. Rain values can vary from, depending on whether mountains cause orographic precipitation. Frontal cyclones can be common in marine west coast regions, with some areas experiencing more than 150 rainy days annually, but strong storms are rare.
File:Zennor, from Zennor Hill - geograph.org.uk - 633.jpg|thumb|Zennor, United Kingdom
Cfb climates are predominant in most of Europe except the northeast, as global temperatures became warmer towards late 20th and early 21st century. They are the main climate type in New Zealand and the Australian states of Tasmania, Victoria, and southeastern New South Wales. In North America, they are found mainly in Vancouver Island and neighbouring parts of British Columbia, as well as many coastal areas of southeast Alaska. There are pockets of this iteration of Cfb climates in South American countries, mostly in regions of southern Chile and Argentina, parts of the provinces of Chubut, Santa Cruz, and southeast Buenos Aires province in Argentina. In Western Asia, the climate can be found on the Black Sea coast of northern Turkey and Georgia, often transitional to humid subtropical. While Cfb zones are rare in Africa, one dominates the coastline of the Eastern Cape in South Africa.
The climate subtype can also be found in Nantucket, Massachusetts and the southern Appalachians, both in the eastern United States. It is also found in the highest portions of the Brazilian state of Bahia and Roraima, Brønnøy Municipality in Nordland at 65.28 °N, the provinces of Sabah, and Baluchistan, Pakistan. Although there are more or less rare places associated with relatively isolated mountainous regions.