The Southern Alps is a mountain range which runs along the western side of the South Island of New Zealand. It forms a natural dividing range along the entire length of the South Island. The term "Southern Alps" generally refers to the entire range and separate names are given to many of the smaller ranges that form part of the Southern Alps.

Aoraki/Mount Cook is the highest point, 3,754 metres (12,283.3 feet). There are sixteen other points in the range that are over 3,000 metres in height. A large proportion of the range is protected as part of various national parks, notably the Westland National Park and Aoraki/Mount Cook National Park.

The Southern Alps were named by Captain Cook in 1770, who described their 'prodigious height'. The had previously been noted by Abel Tasman in 1642, who described the South Island's west coast as 'a land uplifted high'.

Because of its orientation perpendicular to the prevailing westerly winds, it creates excellent wave soaring conditions for glider pilots. The town of Omarama, in the lee of the mountains, has gained an international reputation for its gliding conditions. The prevailing westerlies also create a weather pattern known as the Nor'west arch, in which moist air is pushed up over the mountains, forming an arch of cloud in an otherwise blue sky. This weather pattern is frequently visible in summer across Canterbury and North Otago. The 'nor'wester' is a fohn wind similar to the Chinook of Canada where mountain ranges in the path of prevailing moisture laden winds force air upwards, thus cooling the air and condensing the moisture to rain, producing hot dry winds in the descending air lee of the mountains.