Arctic Maritime

Arctic maritime air is a more direct form of Polar maritime. Its source region lies over the Arctic Ocean close to the North Pole.

The typical pattern that would favour an outbreak of Arctic maritime air is one where there is high pressure to the west of Ireland with low pressure over eastern Europe and southern Scandinavia. Its characteristics are similar to polar maritime air, but because of the shorter sea track the air is colder and has a lower humidity.

Between October and early May, the air is cold enough to produce hail showers or snow, and these are most frequent over Scotland and along the coasts exposed to northerly winds. Polar low-pressure systems forming in this air mass can sometimes lead to widespread and heavy snowfall, but otherwise inland areas remain free of cloud in the winter months. In northern Scotland, arctic maritime is usually the coldest air mass, but over the rest of Britain, this air mass is not generally as cold as polar continental.

Arctic air is uncommon during the summer, but when it does occur it may bring heavy showers or thunderstorms and unseasonably low temperatures.