Oceanic and Marine West Coast Climates

The oceanic or marine west coast climate (Köppen Cfb, with a cooler subpolar variant Cfc) occupies the windward, west-facing coasts of continents in the mid-latitudes, typically between about 40 and 60 degrees, where the prevailing westerly winds arrive off the ocean rather than off the land. This onshore flow, combined in most cases with a warm poleward-flowing ocean current just offshore, produces a climate with an unusually small annual temperature range for its latitude: London averages about 5°C in January and 18°C in July, a spread far narrower than found at similar latitudes deep in continental interiors. Precipitation, unlike in Mediterranean climates at slightly lower latitudes on the same coasts, is distributed fairly evenly across all twelve months, though many locations still see a modest autumn or winter maximum tied to the more active passage of mid-latitude frontal cyclones during the cooler half of the year.