What's the climate like in New Zealand?

Since the Maori people named New Zealand ‘Land of the Long White Cloud’, climate has been of paramount importance to the people of New Zealand — many of whom make their living from the land. New Zealand has mild temperatures, moderately high rainfall, and many hours of sunshine throughout most of the country. Its climate is dominated by two main geographical features — the mountains and the sea.

New Zealand has a largely temperate climate. While the far north has subtropical weather during summer, and inland alpine areas of the South Island can be as cold as —10°C in winter, most of the country lies close to the coast, which means mild temperatures, moderate rainfall, and abundant sunshine.

Because New Zealand lies in the Southern Hemisphere, the average temperature decreases as you travel south. The far north of the country has an average temperature of about 15°C, while the deep south has a cooler 9°C average. January and February are the warmest months of the year, and July is the coldest.

You also asked about plant hardiness as compared to the US. You can basically assume that plants which grow comfortably in New Zealand's centre landscapes, which are mountainous and can experience severe winters with snow and ice, should be fine almost anywhere in the mid- to southern US. On a gut feeling, I'd be inclined to say, if it grows in New Zealand, it will be fine in states like California, Oregon, and Washington to a certain point. Winds and sea air are usually an asset, too.