Cat Ba Island has a tropical monsoon climate: summer from May through July, autumn from late August through October, winter from November through February, spring from February through April. From June through October or sometimes November, Cat Ba Island may be affected by tropical depressions or typhoons. It may rain for 3-7 days when affected by a typhoon or tropical depression. During the time under the effects of a typhoon, traveling by boat between the island and inland are forebidden.