It really depends on what you would like to see! Although it is colder, the glaciers in the South Island are most impressive in winter (July and August). There are also some amazing ski resorts for ski bunnies and shredders on both the North and South Islands. Plus there is less competition for car hires and accommodation at this time of year. December and January are the warmest months, with beautiful weather for hiking and surfing. However, competition for resources is fierce and prices tend to increase significantly due to increased demand. At this time of year, you should plan ahead to ensure you don’t miss out.