In terms of rainfall, Marlborough consists of three climate zones: the dry Wairau valley and its surrounds, a wet Kaikōura coast and a wetter northern zone.
Hot enough for you?
The Awatere valley has experienced New Zealand’s highest recorded temperature – 42°C – equal with two locations in inland Canterbury.
Blenheim’s average annual rainfall of 711 mm is characteristic of the eastern side of New Zealand and is coupled with high sunshine hours – often the nation’s highest.
Picton, like the rest of the Marlborough Sounds, has a higher rainfall and more moderate climate than Blenheim, and is neither as cold in winter nor as hot in summer as the Wairau valley. Kaikōura gets less rain than Picton, but still has an average annual rainfall of 710 mm.
On 3 February 1868 Blenheim was affected by severe flooding. The Marlborough Express reported that Blenheim was submerged, except for the buildings on one ridge, and that the partly built Presbyterian church floated off its piles and down the river, eventually crashing into the Ōmaka River bridge. ‘[C]attle, sheep and pigs came along swimming for dear life – whole stacks of fencing, timber, and firewood, furniture, boxes, &c., all drifting onwards to the great deep.’1
The alluvial Wairau plain is very low-lying and subject to flooding. A major flood occurred in 1868 when an unusual weather pattern caused the Taylor and Wairau rivers to flood simultaneously.
From 1921 the Wairau River Board (known as the Marlborough Catchment and Regional Water Board from 1956 to 1989) engaged in extensive flood-control works. The biggest flood-control measure was the 1963 cutting of a diversion for the Wairau River from Tuamarina to Cloudy Bay.
The Wairau Lagoons (also called the Vernon Lagoons) and Lake Grassmere are both bays cut off by current-borne sedimentation. Lake Grassmere is now used for the production of salt, but the Wairau Lagoons are a wetland management reserve. Grovetown Lagoon is a man-made, cut-off meander loop of the Wairau River.
At the time of European arrival in the mid-19th century, the northern zone was covered in mixed podocarp and beech forest, with subalpine vegetation on the highest peaks of the Richmond Range and on the summit of Mt Stokes in the Sounds. The southern zone was much dryer. It was mostly tussock and subalpine grassland, with some higher-rainfall areas of forest along the Kaikōura coast and in some inland valleys.
The forests in much of the northern zone were cleared for farming in the later 19th century. Original forest survived in the Richmond Range and in high-altitude parts of the Sounds. Titirangi, a rare hebe, is endemic to Hokianga Harbour in Northland, but is also found in a few locations in the Sounds, where it was introduced by Māori.
From the 1970s onwards extensive tracts of scrubland in the Sounds and on the margins of the Richmond Range were planted in radiata pine, a commercial forestry crop.
Little native forest survives in the southern zone – much of the original vegetation was burnt in an attempt to clear the matagouri and Spaniard, prickly plants which impeded access. The impact of humans and grazing animals has accelerated erosion, forming large gullies and fans, and filling the river flats and gorges with shingle. The rock daisy, and the pink and weeping broom, are endemic to the southern zone.
The Marlborough green gecko is found in mānuka shrubland and coastal scrub around the Sounds. The king shag is endemic to the Sounds, and the Hutton’s shearwater to the Seaward Kaikōura Range.
Marlborough has been home to some well-known cetaceans (dolphins and whales). In Māori tradition the taniwha Tuhirangi (which was probably a dolphin) guided the navigator Kupe to New Zealand. Kupe left Tuhirangi to guide waka through Te Aumiti (French Pass), between D’Urville Island and the mainland. The taniwha lived in a cave called Kaikaiawaro.
From 1888 to 1912 a dolphin nicknamed Pelorus Jack guided vessels into the approaches to French Pass from the north. Māori recognised Pelorus Jack as the return of the taniwha Tuhirangi. In the late 20th and early 21st centuries regular sightings of whales and other cetaceans drew visitors to Kaikōura.