Because of its exposure to disturbed weather systems from the Tasman Sea, this climate zone is often quite windy, but has few climate extremes. The most settled weather occurs during summer and early autumn. Summers are warm. Typical summer daytime maximum air temperatures range from 19°C to 24°C, seldom exceeding 30°C. Winters are relatively mild in New Plymouth and Wanganui, but cooler in Palmerston North and Wellington. This is normally the most unsettled time of the year. Typical winter daytime maximum air temperatures range from 10°C to 14°C. Frost occurs inland during clear calm conditions in winter. Annual sunshine hours average about 2000 hours, but inland at Palmerston North it is much cloudier. Northwesterly airflows prevail. Sea breezes occasionally occur along the coast during summer.