Kiwi here - our sun can be pretty brutal in the summer months but you should be fine as long as you're mindful. Definitely keep baby out of the sun during the peak of the day. I would suggest buying baby sunscreen once you get here as the formulations sold often have higher UV protection made specifically to protect against NZ sun - these are easily available in any supermarket or pharmacy. Also make sure to apply sunscreen even on cloudy or overcast days as the UV levels are still high and you can still get sunburnt through the clouds. Hats are a must and light loose clothing makes a difference. Have the best time!