What is the Weather in New Zealand?

New Zealand has a complex climate which varies from sub-tropical in the North to a temperate oceanic climate in the rest of the country and the South Island in particular. This therefore results in mild temperatures all year round and fairly high rainfall.

In terms of temperatures, it is never too hot or too cold all year round - the average temperature is 14°C.
In terms of precipitation, it varies from 600mm to 1600mm of rain per year.

The average temperatures are quite similar when compared with continental Europe but the amplitude is much less marked. This means that it will be much less colder in winter in New Zealand than in continental Europe but it will be warmer in continental Europe in summer. In other words, it's never too cold in winter and never too hot in summer.

In winter, this is excellent news. On average in winter on the North Island it is around 15°C and on the South Island around 10°C (outside the mountains). In summer, temperatures increase but remain pleasant without extremes, on the North Island the average temperatures are around 23°C and on the South Island around 20°C.

You should know that the intensity of the sun is very strong in New Zealand: as soon as it appears, the temperature felt increases sharply. So even with an average temperature of around twenty degrees in summer, the sun adds a feeling of around ten additional degrees. Be sure to cover yourself with sunscreen to avoid sunburn.

Then as soon as the sun disappears in the evening or on cloudy days, the average temperatures below are the norm.

In summer, it's nice and hot during the day, take shorts and T-shirts. As soon as the sun sets, the evenings are cool and you will need a good sweater or fleece jacket. Also take a raincoat because you will get rain even in summer - fortunately it is mostly showers which pass quickly.
Your suitcase will be made up of 70% summer clothes, 20% mid-season clothes and 10% winter clothes (a hat, a big sweater and a rain jacket)

In winter, it is cool on the North Island and cold on the South Island, but if the sun is out, it is not uncommon to dress in shorts and a T-shirt. Take warm clothes but also a warm raincoat or a fleece jacket + light raincoat combination.  
Your suitcase will be made up of 70% winter clothes, 20% mid-season clothes and 10% summer clothes (shorts and T-shirt)

In spring and autumn, you need to prepare for the 4 seasons that will be present during your trip.
You will have summer days, winter days and everything in between.
Your suitcase will be made up of 25% winter clothes, 50% mid-season clothes and 25% summer clothes.

 

If we only look in terms of weather, December, January and February are the best 3 months to travel in New Zealand. You will have the least amount of rain and the highest temperature. However it is also the busiest season in terms of tourists visits and Kiwi holidays, so expect higher price for rentals and less availabilities. 

Now if we look at the weather and ease of travel, November and March are 2 excellent months to visit the country. The weather is good overall, the prices are reasonable and it is not busy.

October and April have colder weather in the South Island, however they are also 2 good months to travel in New Zealand. In April the temperature is nice in the North island. The price for the rentals are going down.

September is the end of winter and beginning of spring, it is still cold but the vegetation comes back to life. There are plenty of nice days if you don't mind the rain. 

May, June, July and August is winter. It is cold and raining. Motorhome's rental rates are at the minimum. It is an excellent period to go skiing.