Mean annual temperatures range from 10°C in the south to 16°C in the north of New Zealand. The coldest month is usually July and the warmest month is usually January or February. In New Zealand generally there are relatively small variations between summer and winter temperatures, although inland and to the east of the ranges the variation is greater (up to 14°C). Temperatures also drop about 0.7°C for every 100 m of altitude.
Sunshine hours are relatively high in areas that are sheltered from the west and most of New Zealand would have at least 2000 hours annually. The midday summer solar radiation index (UVI) is often very high in most places and can be extreme in northern New Zealand and in mountainous areas. Autumn and spring UVI values can be high in most areas.
Mean temperatures
North Island: 16 degrees
South Island: 10 degrees
Summer - Dec, Jan, Feb
Summer months in New Zealand are typically December, January and
February.The hottest weather can be found in regions like Central Otago,
Nelson or Marlborough, the Bay of Islands and Whangarei however the
Canterbury plains are also known to heat up mid summer. New Zealand's
summer heat does not present much humidity, it is a comparatively dry
heat especially the further south you travel. Temperatures do tend to
drop at night time so be sure to take a sweatshirt with you on day\night
excursions. Temperatures generally range between 20-30ºC
Winter - Jun, Jul, Aug
Winters can be bitterly cold in New Zealand - you will need your
thermals. The South Island in particular reaches some extreme lows -
however the middle of the North Island can also experience winter
weather which closes roads and causes havoc to farming communities.
Places like Kaikoura, Wellington and Dunedin are known for icy cold
winds and many New Zealand regions experience hard frosts.
Temperatures generally range between 10-15ºC.
Spring - Sep, Oct, Nov
Temperatures can be reasonably warm yet evenings cool right down.
Late snowfalls have been known to keep some skifields open during this season.
Autumn - Mar, Apr, May
Autumn temperatures are quite crisp and warm clothing is advised if
travelling in New Zealand especially near the later part of this
season.
