New Zealand is in the Southern Hemisphere, so its seasons are the opposite of the Northern Hemisphere. This means a New Zealand winter is from June–August, with the coldest month in July.
Winter temperatures are generally cool, but they vary considerably by region. The alpine conditions of the Southern Alps, for example, are very different from the subtropical climate of the far north. Or to put it another way: gloves and a woolly hat have a utilitarian purpose in Queenstown, but they are usually worn to complete an outfit in Auckland.
New Zealand’s varied climate is caused by a bunch of factors best explained by meteorologists. But, put simply, it has to do with latitude, the surrounding ocean, prevailing westerly winds, and New Zealand’s rugged topography – i.e., mountain ranges that begin at sea level. Basically, New Zealand is home to a lot of microclimates.
Average winter temperatures by region:
City Min Max
Auckland 8°C (46°F) 16°C (61°F)
Wellington 7°C (45°F) 12°C (54°F)
Queenstown 0°C (32°F) 8°C (46°F)
Invercargill 1°C (34°F) 10°C (50°F)