Despite Iceland's northern latitude, its climate is fairly mild because of the Gulf Stream, part of which almost encircles the island. There are no extreme temperature variations between seasons, but frequent weather changes are usual, particularly in the south, which experiences many storms and heavy precipitation. Temperatures at Reykjavík range from an average of 11° C (52° F ) in July to -1° C (30° F ) in January, with an annual mean of about 5° C (41° F ). Humidity is high, and there is much fog in the east. Annual rainfall in the north ranges from 30 to 70 cm (12–28 in); in the south, 127–203 cm (50–80 in); and in the mountains, up to 457 cm (180 in). Winters are long and fairly mild, summers short and cool. Summer days are long and nights short; in winter, days are short and nights long.