Manawatu-Wanganui is a region in the lower half of the North Island of New Zealand, whose main population centres are the cities of Palmerston North and Whanganui.
It is administered by the Manawatu-Wanganui Regional Council, which for trading purposes is known as Horizons Regional Council.
In recent years both the Whanganui River and Whanganui District have been renamed.
The region covers all or part of ten territorial authority areas. Parts of five of these are covered by five other regions of New Zealand, the most of any region.
In descending order of land area the territorial authority districts are Ruapehu, the major parts of Tararua and Rangitikei, Manawatu, Whanganui, Horowhenua, small parts of Stratford, Waitomo, and Taupo.
The largest city is Palmerston North, with a population of 85,300 (June 2012 estimate). It is the only territorial authority in the region to be administered by a city council.
The region is dominated and defined by two significant river catchments, the Whanganui and the Manawatu.
The Whanganui River, in the northwest, is the longest navigable river in New Zealand. The river was extremely important to early Māori as it was the southern link in a chain of waterways that spanned almost two-thirds of the North Island. It was one of the chief areas of Māori settlement with its easily fortified cliffs and ample food supplies.
Legends emphasise the importance of the river and it remains sacred to Whanganui iwi. Māori along the coast and lowland plains grew kumara and other crops. The Manawatu River runs across the centre of the region, from rolling hill country in the east to the fertile Manawatu Plains in the west.
The main city of Palmerston North is located on these plains, and is an important service city for the southern North Island as a whole. This river is unusual, in that it passes from hill country to plains through a gorge cut into much higher country, an indication that the hills have risen since the river formed.
Manawatu-Wanganui takes up a large proportion of the lower half of the North Island. It is the second-largest local government region in the North Island and the sixth-largest in New Zealand, totalling 22,215 km2 (8.1% of New Zealand's land area).
The region stretches from north of Taumarunui to south of Levin on the west coast, and across to the east coast from Cape Turnagain to Owhanga.
It borders the Waikato, Taranaki, Hawke's Bay and Wellington regions and includes river catchment areas that run from the volcanic plateau to the sea. The Pacific Ocean is the eastern boundary and the Ruahine Ranges form a natural boundary with Hawke's Bay.
The area includes a variety of landscape formations. Districts close to the Volcanic Plateau are higher and more rugged, often subject to harsh temperatures in winter. The Manawatu District has a much gentler topography, consisting mainly of the flat, tree-studded Manawatu Plains that run between the ranges and the sea.
The land was under the sea till about 500,000 years ago and still has a very thick layer of marine sediment, which is about five or six million years old.
Soils are productive with the addition of fertiliser. In the Manawatu and Horowhenua Districts there are sandy soils and swampy hollows around the coast with loess-covered terraces and river flats inland.
These river flats and swamp areas contain fertile alluvial and organic soils. On the drier terraces inland yellow-grey earths predominate.
The flatter more fertile soils suit intensive sheep farming and cropping while the hill country of Rangitikei favours semi-intensive sheep and beef farming. Areas close to the volcanic plateau consist largely of pumice soils which lack some essential trace elements but within the region much of this land is occupied by national parks.
The region has a comparatively mild climate with greater climatic extremes inland. Chateau Tongariro experienced the lowest temperature recorded in the North Island, falling to -13.6 °C on 7 July 1937.
In summer the region is warm, with a maximum mid-summer daily average of between 20.1 and 22.9 °C. Sunshine hours approximate the national average for much of the region (1,800-2,000 hours per annum) but Palmerston North is defined as cloudy with an average of 1,725 sunshine hours.
In the winter the minimum mid-winter daily average for coastal areas is 4.0 to 7.9 °C, while inland areas are considerably colder.
Waiouru has a minimum mid-winter daily average of 0.1 °C.
Rainfall on the plains is slightly below average, with Palmerston North receiving 960 mm, while the rest of the region receives the New Zealand average rainfall of 1,000-2,000 mm.