Otago, in particular Central Otago, has some of New Zealand’s highest and lowest temperatures, and its lowest rainfall. As an elevated region, relatively distant from the ocean, Central Otago has a more continental climate than any other area of the country.
Inland temperature extremes
In July, the coldest month, the average maximum temperature in Alexandra is only 8.1ºC – one of the lowest in New Zealand. Ranfurly, north-east of Alexandra, has registered the country’s lowest recorded temperature of -25.6ºC.
Alexandra's average maximum temperature in January, the hottest month, is 25.1ºC – much hotter than Otago’s coastal districts. Alexandra’s highest temperatures in summer can exceed 37ºC – equal to Timaru, and lower than only Gisborne and Christchurch. Alexandra also has a much higher proportion of days over 30ºC than Auckland, which is 1,000 kilometres further north.
The winterless south?
The City of Dunedin website claims that Dunedin is known for its ‘ideal winter weather and warm summer months … a subtropical marine climate’. 1 Sadly, it’s not Dunedin, New Zealand, but Dunedin, Florida. The American city was founded by two Scots in 1899, and – like its chillier New Zealand namesake – acknowledges its origins with Highland games, bagpipes and marching bands.
Cool on the coast
Coastal Otago’s climate is moderated by the ocean, but is significantly cooler than coastal regions further north. Dunedin’s mean January temperature is 15.3ºC, compared with 17.5ºC in Christchurch and 19.1ºC in Auckland. Its July mean of 6.6ºC is the same as Christchurch but is well below Auckland’s 10.9ºC.
Dunedin averages 1,682 sunshine hours annually – far lower than Alexandra, which has 2,005.
Parts of Central Otago have New Zealand’s lowest rainfall by far. Alexandra’s 359 millimetres is well below the country’s next lowest centre (Timaru, with 548 millimetres). Queenstown, closer to the west coast, and Dunedin, on the east coast, receive 749 and 738 millimetres of rain respectively – still dry compared with the western South Island and the North Island.
When humans first arrived in Central Otago, it was probably covered in forests of mataī and tōtara. However, Māori burnt much of the forest, which was unable to regenerate in the dry climate, and tussock took its place. Today tussock is most common on the heights. The lower-lying parts of Central Otago are planted in pasture with stands of orchard and shelter trees. These, particularly poplars, display dramatic colour changes in late autumn.
Introduced grasses are also characteristic in coastal North and South Otago, although there are significant stands of native forest in the Catlins district, and plantation forests around Tapanui and in other districts closer to Dunedin. Some pasture in the Catlins has reverted to mānuka and eventually to forest.
Beech forest grows on the Otago section of the Southern Alps, between 800 and 1,200 metres. Higher up this gives way to tussock, then subalpine plants, and then bare rock and snow.
Erosion, triggered by rabbits and the replacement of tussock by pasture, has limited livestock-carrying capacity in many areas. Stock have subsequently been concentrated in areas favourable to pasture growth. Cultivating lucerne (alfalfa) for winter fodder has boosted carrying capacity. Irrigation has helped develop orchards in the Clutha valley, and has also been used for some pastures, especially in the Ida valley.
Central Otago was once an important habitat for moa. Today it is home to smaller animals, notably skinks. The rare Cromwell chafer beetle is found only in a small area near Cromwell. Coastal Otago is home to seal and penguin colonies – including the rare yellow-eyed penguin – and to the royal albatross breeding grounds at Taiaroa Head.