Figure 3.6: New Zealand nationally-averaged frequency of days per year with daily minimum temperature below the 1961-1990 5th percentile
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Note: This calculation has been undertaken over the period 1951-98 separately over 21 sites, including outlying islands, and then aggregated to produce this figure. The straight trend line is a least squares fit to the annual values. The 5th percentile of daily minimum temperature at any location is that minimum temperature for which only 5% of days are colder over the reference period (in this case 1961-1990). Figure taken from Salinger and Griffiths (2001).
Text description of figure
Nationally-averaged frequency of days per year with daily minimum temperatures below the fifth percentile have decreased steadily from about 24 days in the early 1950s to around 15 days in the late 1990s. A linear trend line fitted to the data is superimposed on the yearly variability and highlights this decrease in "frost days" at many sites in New Zealand. Note: This calculation has been undertaken over the period 1951-98 separately over 21 sites, including outlying islands, and then aggregated to produce this figure. The straight trend line is a least squares fit to the annual values. The 5th percentile of daily minimum temperature at any location is that minimum temperature for which only 5% of days are colder over the reference period (in this case 1961-1990).
