In general Southland has a cool temperate climate. In the populated and intensively farmed parts of the region mean daily temperatures range from around 5ºC in July to14ºC in January. There can be around 80 days of ground frost in the winter months and 1000mm of rainfall fairly evenly spread throughout the year. Wind speed averages 15–20km/hr and there are about 1600 hours of sunshine annually. In the alpine areas and over in Fiordland the climate is more extreme.
However, such a generalisation takes no account of the variations imposed by elements of geographical location and topography. Closer scrutiny reveals a tremendous variety of microclimates that can be exploited to advantage by the discerning land user or, equally, may cause problems for the unwary.
Microclimates – the Topoclimate Survey
The climate component of the Topoclimate Survey of Southland involved the placement of temperature dataloggers at approximately 3,000 locations throughout the region measuring air temperatures and, at some sites, soil temperatures for a year. The data were then processed by statistical comparison against the nearest long term weather station to produce a synthetic thirty-year temperature record for the datalogger location.
Climatologists then interpreted these data to produce Growing Degree Day Maps, which estimate the zones of heat units available for plant growth. The ultimate aim was to recognise the thousands of microclimates in the landscape and optimise land use by matching crops to microclimates.
Use the links below to learn more about Growing Degree Days (GDD) or to browse the interactive heat (GDD) maps.