Keelung has a humid subtropical climate and is particularly noted for its high rainfall year-round, with an average of upwards of 3,700 millimeters (146 in), contributing to its nickname of "Rain Port". Winters are short and mild, whilst summers are long and hot, much like the rest of the island. However its location on northern mountain slopes means that due to orographic lift, rainfall is heavier during fall and winter, the latter during which a northeasterly flow prevails. During summer, southwesterly winds dominate and thus there is a slight rain shadow effect. Fog is most serious during winter and spring, when relative humidity levels are also highest
