Squamishes occur in those fjords oriented in a northeast–southwest or east–west direction where cold polar air can be funneled westward, the opposite of how the wind generally flows on the Coast.
[1] These winds in winter can create high windchills[clarification needed] by coastal standards of −20 to −30 °C (−4 to −22 °F).
Squamishes lose their strength when free of the confining fjords and are not noticeable more than 25 km offshore.
In Northern Washington including Lynden and Bellingham, and Lower Mainland, including Eastern Vancouver Island, of British Columbia, they are mainly referred to as outflow winds, they are noticeable especially in the winter, when a cold Arctic air mass holding in the high plateau country of the interior flows down to the sea through the canyons and lower passes piercing the Coast Mountains and crossing the Strait of Georgia.
During the Christmas season of 1996, a major blizzard which brought record snowfalls to the Lower Mainland and Eastern Vancouver Island was followed up by hurricane-force winds pouring west through the towns of the Fraser Valley, as the coastal system's strength – which had brought the snow – was forced back by the breaking of the interior's cold air mass.