Climate of Norfolk IslandNorfolk Island sub-tropical climate is tempered by the surrounding sea. The climate of Norfolk Island is principally affected by the belt of high pressure systems which oscillate north and south over the Island annually.
Temperatures: Diurnal and annual temperature ranges are small. Average maximum temperatures range from 18C to 19C in winter to between 23C and 25C in summer. The highest temperature ever recorded was 28.4C on 11th Feb 1996. Average minimum temperatures range from 13C to 15C in the winter and between 18C and 20C in the summer. The lowest temperature ever recorded was 6.2C on 29th July 1953.
Rainfall: The median annual rainfall for Norfolk Island is 1302mm, and the annual mean rainfall is 1312mm. Rainfall is greatest during the four months from May to August, with monthly long-term means of about 130 to 147mm. Minimum monthly rainfall, averaging 75 to 87mm occurs from November to January. The wettest month is June having an average 147mm and the driest month is November having an average of 75mm. The highest monthly rainfall was 473.2mm in December 1989. Norfolk Island averages 181 rain days per year, ranging from an average of 10 rain days in November to 21 rain days in July.
Humidity: Relative humidity is generally high. The relative humidity averages in the 74% to 79% range at 9am and in the 71% to 74% range at 3pm.
Wind: Winds are predominantly east to south-east during summer and autumn swinging to the south to south-westerly in winter and returning to the south in spring. The maximum wind gust recorded on Norfolk Island was 135km/h from the SSW on 19th March 1992.
Thunderstorms: Thunderstorms are most prevalent during the winter and spring, with an average of 12 thunderstorms per year. Hail occasionally accompanies thunderstorms in winter, with an average of one hailstorm per year.
Cyclones: Tropical cyclones are some, but occasionally have an influence in the early months of the year. Mid latitude depressions move in from the Australian continent or southwest Tasmanian Sea and effect the island mostly from February to August.