Figure 3.7: Frequency of days per year with daily minimum temperature below 0°C

Text description of figure

This figure shows 2 plots of frequency of days per year with daily minimum temperature below 0°C. In the top panel, both the Canterbury and Marlborough regions show about 20 fewer frosts per year now than in the early 1970s.

However, the change in frost occurrence is not uniform, and shorter periods can give counterintuitive results. The upper panel also shows an increase since 1972 in the frost incidence in the Wellington region, which is due to increases in the eastern (Wairarapa) side of the lower North Island. This tendency for increased frost since 1972 is also evident in other east coast sites, including Gisborne, south Canterbury and coastal Otago.

However, even for these sites, there has been a decrease in frosts on the longer timescale. An example of this sort of trend is shown for Dannevirke in the lower panel.