The sunniest areas are to be found locally near Blenheim, Nelson, and Whakatane, where the average duration of bright sunshine exceeds 2,400 hours per annum. Napier and the rest of the Bay of Plenty are only slightly less sunny. A large portion of the country is favoured with at least 2,000 hours. Even Westland, despite its high rainfall, has 1,800 hours. Southland, where sunshine drops sharply to 1,700 hours per annum, lies on the northern fringe of a broad zone of increasing cloudiness. Four hundred miles further to the south, at Campbell Island, the sunshine has the extremely low value of 650 hours per annum. A pleasant feature of the New Zealand climate is the high proportion of sunshine during the winter months. To eliminate the effect of varying day length, the summer and winter sunshine at a few selected stations have been expressed as a percentage of the possible sunshine.
As these figures indicate, there is a marked increase in cloudiness in the North Island in winter, but little seasonal change in the South Island, except in Southland.
by Neil George Robertson, M.SC., Assistant Director (Climatology), Meteorological Service, Department of Civil Aviation, Wellington.
- New Zealand Journal of Science and Technology, Vol. 12 (1930), “The occurrence of Thunderstorms in New Zealand”, Kidson, E., and Thomson, A.
- Ibid, Vol. 13 (1931), “Mean Temperatures in New Zealand”, Kidson, E.
- Ibid, Vol. 14 (1932), “The Frequency of Frost, Snow and Hail in New Zealand”, and “The Canterbury Northwester”, Kidson, E.
- Ibid, Vol. 22B (1940), “The Variations of Annual Rainfall in New Zealand”, Seelye, C. J.
- Ibid, Vol. 27B (1946), “Variations in Monthly Rainfall in New Zealand”, Seelye, C. J.
- Ibid, Vol. 32B (1950), “Droughts in New Zealand”, Bondy, F.
- New Zealand Geographical Society Miscellaneous Series No. 1 (1950), “The Climates of New Zealand according to Thornthwaite's Classification”, Garnier, B. J.
- New Zealand Meteorological Service Note No. 33 (1947), “The Frequency of Heavy Daily Rainfalls in New Zealand”, Seelye, C. J.
- Ibid, No. 43 (1956), “The Estimation of Natural Evaporation and Water Need”, Gabites, J. F.
- New Zealand Journal of Science, Vol. 4 (1961), “Estimation of Open Water Evaporation in New Zealand”, Finkelstein, J.