The sea water has a stable temperature and is separated into four distinct layers as follows. The top are surface water which has a temperature of in summer and in winter. The next layer is formed by the inflows from the Pacific Ocean and Bering Sea coming through the Bering Strait; it extends up to the North Pole. The warmest, deep Atlantic layer has the temperatures between 0 and 1 °C (32 to 34 °F), and water at the bottom is a bit colder at −0.4 to −0.8 °C (31.3 to 30.6 °F). The average salinity varies between 28‰ and 32‰ (parts per thousand) from south to north. Typical air temperatures (at Tuktoyaktuk) are in January and in July.